I never could figure out where would OP_CODESEPARATOR be useful and some very old comments from early days suggest it may be a byproduct of a bad decision (eg. scripts were concatenated then executed at first).
While going through Taproot this OP code makes even less sense in Tapscripts and yet it is there. So I was wondering if I'm missing something and whether there is any good script examples I could look at where OP_CODESEPARATOR solves a problem that can't be solved in any other way.