EDIT: @mindbleach@sh.itjust.works shared something that might help to circumvent this shit:
Contained in these parentheses is a zero-width joiner: (โ)
Basically, add those to whatever you feel that might be filtered out, then remove the parentheses. The content inside the parentheses is invisible, but it screws with regex rules.
If it weren't working your code wouldn't count an additional character on the first string.
Anyway, this is the character., as it seems that deleting the first parenthesis also deletes the ZWJ.