How to disable option+f1 shortcut?
That's not actually on  Opt ⌥   F1 , it's on the "special functions" keys, so it's triggered by the  symbol rather than the actual F-Key.

To get the 'true' F-key you could either press  Fn   Opt ⌥   F1  or alternatively swap all your F-key Functionality in System Prefs > Keyboard > Keyboard



 sorry for the emoji, couldn't find anything better ;-)