Serialization error when editing an asset with a class starting with the same name as the namespace that it is in

Unity: Serialization

2023.2.X

2023.2.0b1 onwards

6.2.X

6.1.X

6.0.X

Reproduction steps:
1. Open the attached project "ErrorProject"
2. Enter The Play mode
3. Observe Console

Expected result: No errors
Actual result: Scripted class MyNamespace.MyNamespace.class is serialized as MyNamespace.lass and an error appears

Reproducible with: 2023.2.0b1, 6000.0.20f1
Not reproducible with: 2021.3.43f1, 2022.3.48f1, 2023.2.0a23
Couldn’t test with:

Reproducible on: Windows 11
Not reproducible on: No other environment tested