A new UnityDefaultRuntimeTheme keeps getting created regardless of its existence when the UI Builder window is opened

How to reproduce:

1. Open “UXMLDefaultRuntimeTheme bug.zip“ project
2. If “UnityDefaultRuntimeTheme 1.tss” file exists in the Assets folder of the Project window, delete it
3. Open the UI Builder window (Window > UI Toolkit > UI Builder)
4. Observe the Project window

Expected results: The existing “UnityDefaultRuntimeTheme.tss” file will be used
Actual results: A new “UnityDefaultRuntimeTheme 1.tss” file is auto-generated

Reproducible in: 2022.3.11f1, 2022.3.14f1, 2023.2.1f1, 2023.3.0a16
Not reproducible in: 2021.3.32f1, 2022.3.10f1

Reproduced on: Windows 11 Pro
Not reproduced on: No other environment tested

Note:

• The issue is also reproducible while in Play Mode