Reproduction steps:
1. Open the attached project “USSFileProject”
2. Open the “Assets/Scenes/SampleScene” scene
3. Open Open the UI Toolkit Debugger window (Window > UI Toolkit > Debbuger)
4. In the Panel dropdown choose “PanelSettings”
5. Select an element in the visual tree hierarchy pane
6. Inspect the Stylesheets list

Expected result: Only 2 or 3 Stylesheets are visible
Actual result: All of the imported Stylesheets are visible

Reproducible with: 2021.3.23f1, 2022.2.16f1, 2023.1.0b13, 2023.2.0a12
Couldn’t test with: 2020.3.47f1 - There is no “PanelSetting” choice in the Panel dropdown menu

Reproducible on: macOS 13.3 (Intel)