Reproduction steps:

# Open the “My Project” attached project
# Open the “SampleScene” scene
# Enter the Play Mode
# Press the button in the middle of the Game view
# Observe the text under the button

Expected result: Text says “ITestInterface.Foo“
Actual result: Text says “TestClass“

Reproducible with: 2021.3.16f1, 2022.2.2f1, 2023.1.0a25
Could not test with: 2020.3.44f1 (Default interface methods are not supported)

Reproduced on: Windows 10

Note: Not reproducible with IL2CPP. Reproducible with Mono in the Player.