Repro steps:
1. Import the attached UUM-49819-DirtyAssets.unitypackage2.
2. Open Window->UI Toolkit->TestAssetDirty
3. Save the scene using file->save
4. Click "Scan for dirty assets"
5. Should show that "everything is clean"
6. Open Editor/TestTemplate in the UIBuilder
7. Press save again to make sure everything is saved
8. Click Scan for dirty assets

Expected: "Everything is clean!"
Actual: "Dirty Asset:Assets/Editor/MainStyle.uss"

Reproducible with: 2021.3.30f1, 2022.3.10f1, 2023.1.15f1, 2023.2.0b11, 2023.3.0a7

Reproducible on: Ubuntu 23.04, Windows 10 Pro 22H2
Not reproducible on: no other environments tested