Yup, I'd had to do just that a few times on onlyfans - one time the creator left me on read for two days and once I sent a screenshot of
that they refunded me right away, but yeah typically they'll give the creator 7 days (must be to account for a period, I've always wondered why 7 days but that's gotta be why, right?) and then they'll refund you if the custom isn't delivered.
I try my best to avoid doing this because I don't want to receive a custom that's filmed with resentment in the girl's mind and/or they just look bored or extra fake in the custom as a sort of revenge for having been told on.
Unethical life tip, one time I had just had it with one girl giving excuses and I didn't even want the custom anymore, so I sent the screenshots to OF support, complaining about not receiving the custom...then I blocked her so she
couldn't deliver anything - that way I got my money back instead of receiving a custom I wouldn't be able to enjoy 'cause I'd be able to tell the girl's pissed off.