Vendors.css origin in react4xp

Enonic version: 7.13.3
OS: Ubuntu 20/04

In this project with react4xp I see that after compiling, there is a css file called vendors.css that was not created by myself in the project. Maybe this is from the compilation of react4xp?
I’m trying to see where this comes from, but searching in the react4xp project for “vendors” shows nothing, googling I was only able to see a single mention in the documentation for the vendors.< contenthash >.js here and nothing about vendors.css.
I suspect that this comes from the compilation of the react4xp. How does the process of generating this vendors.css file work?

Edit: after further investigation, I see that this vendors.css is present in xp/build/resources/main/r4xassets. However, I was not able to see any of the assets used in the files compiled to this vendors.css.
For example: a scss file that imports an image will no longer work because after this compilation to vendors.css, the css rule will now exist the file inside r4xassets, and there will be no image for it’s path to be defined in the css rule, thus breaking the functionality.

React4XP doesn’t have a file called vendors.css. Maybe you meant vendors.js?

Here’s a screenshot of r4xAssets folder after build of the React4XP starter: