@narcell so looking at it a bit more, if you do want to mess with it you can try deleting the exec defaults write $::pd_guiprefs::domain NSRequiresAquaSystemAppearance -bool true
line in pd_guiprefs.tcl.
Then you probably also have to delete the ~/Library/Preferences/org.puredata.pd.pd-gui.plist file, or at least delete the
<key>NSRequiresAquaSystemAppearance</key>
<true/>
in it