Reproduction steps:
1. Download and install "Beyond Compare"
2. Modify lines 15-16 in the "/{PATH_TO_EDITOR}.app/Contents/MacOS/Tools/mergespecfile.txt" file to point to the "bcomp" executable inside of the "Beyond Compare" installation path
3. Open the "IN-90944.zip" project
4. Modify line 14 in the ".git/config" file to point to the UnityYAMLMerge tool from the currently used Editor
5. Run "git checkout main & git merge test & git mergetool" in your Terminal
6. Observe the opened merge tool

Expected result: Beyond Compare is opened
Actual result: FileMerge is opened

Reproducible with: 2021.3.47f1, 2022.3.55f1, 6000.0.32f1, 6000.1.0a9

Reproducible on: macOS 15.1.1 (M1 Max)
Not reproducible on: No other environment tested