• Rollup Version: 2.23.0
• Operating System (or Browser): macOS
• Node Version (if applicable): 10.x - 14.6
• Link to reproduction: https://github.com/lukeed/bug-rollup-css-hashes

Expected Behavior

The generated file hashes should be identical between builds since nothing is changing.

Actual Behavior

Within ~10 builds of the same source files, there will be files that have different build hashes despite having identical output content – or in most cases, identical content except for import statements to other files that also inexplicably change.

In the repro provided (please see readme), there are two files that will have different output hashes within a 10-build loop. They have a maximum of 2 hash variations per file, which I find odd.

It seems to happen with a particular combination of shared dependency trees, dynamic imports, and CSS files (emitted as assets). I dumbed it down considerably, but it's by no means a farfetched application setup.

Thanks~!