I have the same issue. I have updated to 18 Beta on my Iphone 13 Pro and now all my apps are frozen behind the time limit as I can ignore it/change it/remind me/ disable it. When I go try disable it in the settings the whole settings app freezes.

Guys whoever is having those issues I found a temporary bypass. You need to go to settings-general-date&time-change automatic to manual and then pick a time in the next day. Its not ideal as you will have wrong time on device but at least you will be able to use the apps that were blocked by the time limit. I will be trying to restore back to iOS 17 as this issue has been going on for over a month looking at this thread and nothing has been done.