Next.XP Render Error when following a NextLink from a page called dircet

Enonic version: 7.9.2

I have the following part-component:

import React, {useEffect, useState} from 'react';
import {PartProps} from "../../_enonicAdapter/views/BasePart";
import {Box, Grid, Heading} from "@chakra-ui/react";
import {Container} from "@chakra-ui/layout";
import {buildQueryTerms, calculateCursor, pageIndexHelper, parseString} from "../../utils/helpers";
import Pager from "../ui/Pager";
import {useRouter} from "next/router";
import {isArray} from "@chakra-ui/utils";
import GlossaryListFilter from "./GlossaryListFilter";
import {getGlossaryListQuery, IGlossaryListFilter} from "../queries/getGlossaryList";
import {CONTENT_API_URL} from "../../_enonicAdapter/utils";
import {VariablesGetterResult} from "../../_enonicAdapter/ComponentRegistry";
import {GlossaryItem} from "../views/GlossaryItem";

export const GlossaryList = (props: PartProps) => {

    const router = useRouter();

    const {meta, data, part} = props;
    console.log ("Render Mode: ", meta.renderMode);

    // Necessary for EDIT-Mode in Content Studio !!
    if (!router) {
        return <h1>Template Editing Mode ?</h1>
    }

    const {
        term: termFromQuery,
        page: pageIndexFromQuery
    } = router.query || undefined;

    /* todo: extract the following block - also used in MarketNewsArchive */
    let pageIndex: number;

    if (pageIndexFromQuery === undefined || isArray(pageIndexFromQuery)) {
        pageIndex = 1;
    } else {
        pageIndex = parseInt(pageIndexFromQuery)
    }

    /*
    * some local state
    * */

    const [glossaryData, setGlossaryData] = useState(data.queryConnection);
    const [filter, setFilter] = useState<IGlossaryListFilter>({
        term: parseString(termFromQuery)
    })

    const [isFilterActive, setIsFilterActive] = useState(
        termFromQuery !== undefined);

    /************************************************************************/

    const glossaryList = glossaryData.edges;
    const total = glossaryData?.totalCount;
    const pageSize = part.config?.first || 10;

    const getVars = (): VariablesGetterResult => {

        const {page} = router.query;

        const offset = calculateCursor({
            pageIndex: page ? page : 1,
            pageSize: pageSize
        });

        return {
            "path": meta.path,
            "query": `type='de.osde.app.be:glossary' and ngram('*','${filter.term}','AND')`,
            "offset": offset,
            "first": pageSize
        }
    }

    const fetchGlossary = async () => {
        const API_URL = CONTENT_API_URL;
        let resp;
        let total; // total from client fetch
        const vars = getVars();

        try {
            resp = await fetch(API_URL, {
                method: 'POST',
                body: JSON.stringify({
                    query: getGlossaryListQuery,
                    variables: vars
                })
            });

            const filteredGlossary = await resp.json();
            total = filteredGlossary.data.guillotine.queryConnection.totalCount;

            setGlossaryData(filteredGlossary.data.guillotine.queryConnection);

        } catch (e: any) {
            console.error("Failed to fetch data %s", e.errorMessage);
        }

        // todo: also implement for news
        const pageHelper = pageIndexHelper({
            currentPage: pageIndex,
            total: total,
            pageSize: pageSize
        })

        const queryTerms = buildQueryTerms({page: String(pageHelper.page), ...filter});

        await router.push(router.query.contentPath + '/?' + queryTerms.toString(),
            undefined, {shallow: !pageHelper.shouldChangePage});
    }

    useEffect(() => {
        if (isFilterActive) {
            console.log("fetch from client");
            fetchGlossary().then(() => {
                console.log('fetched from client filter=%s, data=%s', JSON.stringify(filter, null, 2), data)
            });
        } else {
            setGlossaryData(data.queryConnection);
        }
    }, [filter, data.queryConnection.total, pageIndex]);

    return (
        <Container maxW={"6xl"}>
            <Heading>Outsourcing Glossar</Heading>
            <Box>{total} Glossareinträge</Box>
            <GlossaryListFilter
                filter={filter}
                setFilter={setFilter}
                setIsActive={setIsFilterActive}
                isActive={isFilterActive}/>
            {/*todo: make /glossar dynamic*/}
            <Pager total={total}
                   url={'/glossar'}
                   filter={filter.term}
                   pageSize={pageSize}
                   pageIndex={pageIndex}/>
            <Grid
                gridTemplateColumns={'repeat(auto-fill, minmax(250px, 1fr))'}
                columnGap='5'
                rowGap={{base: '8', md: '12'}}
                my={10}
            >
                {
                    glossaryList.map((edge: any, key: number) => <GlossaryItem key={key} {...edge} />)
                }
            </Grid>
            <Pager total={total}
                   url={'/glossar'}
                   filter={filter.term}
                   pageSize={pageSize}
                   pageIndex={pageIndex}/>
        </Container>
    );
};


export default GlossaryList;

In the glossary-component which is called by the glossaryItem-component I have the following Link, back to this List.

 <NextLink href={backLink} passHref>
      <Button as={"a"} my={5} colorScheme="brand" variant="outline">
          {glossaryData.parent.displayName}
      </Button>
  </NextLink>

This works as I expected- but when I call the glossary component directly by its url, I get the following warning. When I call from the link in glossaryItem, this warning does not appear.

Warning: React has detected a change in the order of Hooks called by Header. This will lead to bugs and errors if not fixed. For more information, read the Rules of Hooks: https://reactjs.org/link/rules-of-hooks

   Previous render            Next render
   ------------------------------------------------------
1. useState                   useState
2. useContext                 useContext
3. useContext                 useContext
4. useState                   useState
5. useLayoutEffect            useLayoutEffect
6. useContext                 useContext
7. useEffect                  useEffect
8. useContext                 useContext
9. useContext                 useContext
10. useContext                useContext
11. undefined                 useContext
   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    at Header (webpack-internal:///./src/components/ui/layout/Header.tsx:32:63)
    at eval (webpack-internal:///./node_modules/@chakra-ui/toast/dist/chakra-ui-toast.esm.js:465:24)
    at EnvironmentProvider (webpack-internal:///./node_modules/@chakra-ui/react-env/dist/chakra-ui-react-env.esm.js:120:24)
    at ColorModeProvider (webpack-internal:///./node_modules/@chakra-ui/color-mode/dist/chakra-ui-color-mode.esm.js:194:21)
    at ThemeProvider (webpack-internal:///./node_modules/@emotion/react/dist/emotion-element-cbed451f.browser.esm.js:96:64)
    at ThemeProvider (webpack-internal:///./node_modules/@chakra-ui/system/dist/chakra-ui-system.esm.js:70:27)
    at ChakraProvider (webpack-internal:///./node_modules/@chakra-ui/provider/dist/chakra-ui-provider.esm.js:22:24)
    at ChakraProvider (webpack-internal:///./node_modules/@chakra-ui/react/dist/chakra-ui-react.esm.js:253:23)
    at MyApp (webpack-internal:///./src/pages/_app.tsx:58:27)
    at ErrorBoundary (webpack-internal:///./node_modules/next/dist/compiled/@next/react-dev-overlay/client.js:8:20746)
    at ReactDevOverlay (webpack-internal:///./node_modules/next/dist/compiled/@next/react-dev-overlay/client.js:8:23395)
    at Container (webpack-internal:///./node_modules/next/dist/client/index.js:323:9)
    at AppContainer (webpack-internal:///./node_modules/next/dist/client/index.js:825:26)
    at Root (webpack-internal:///./node_modules/next/dist/client/index.js:949:27)

I do not really find this error-stack very helpfull!
Maybe someone had a similar issue and can help!

My first thought was the code at the beginning of the glossaryList, because this violates the rules for hooks.

// Necessary for EDIT-Mode in Content Studio !!
    if (!router) {
        return <h1>Template Editing Mode ?</h1>
    }

Unfortunately or happily disabling these lines does not help. This only leads in an error in Content-Studio in EDIT-Mode.