screen time does not block apps when time is up

I have a 2 hour limit set on Snapchat, and a separate one on TikTok. However it doesn't appear to work, and hasn't for ages. I've seen this reported several times and dismissed as user error, but it isn't. It's buggy software.

When time is up on Snapchat, the app is somehow able to completely ignore it. You don't get prompted to extend time or anything - the developers must've figured out how to bypass this.

Please Apple, sort it out! I'd never recommend anyone letting their kids have an iPhone when the parental controls don't work.