Hash Difference of bundle files built in the same env

[rsgok]

Bug report

What is the current behavior?

build the same project two times in the same environment(in fact, I build in two dockers of completely same env), but the hash tags of some bundle files are different.

If the current behavior is a bug, please provide the steps to reproduce.

1. use this demo project to test demo
2. run npm i && npm build

What is the expected behavior?

same hash tag of bundle files no matter how many times i build

Other relevant information:
webpack version: 4
Node.js version: 14.4
Operating System: docker/linux redhat
Additional tools:

[alexander-akait]

Problem on css-loader side - webpack-contrib/css-loader#886

[alexander-akait]

Please create minimum reproducible test repo in future, I it very hard to catch problem using boilerplates and big projects