If you are in S. Korea, read this support article —> https://support.apple.com/HT209533 = Verify your age when you download or stream mature content in South Korea
If you are seeing this because you are running the beta version of iOS26.4 then you should probably downgrade back to the regular version. We are not allowed to discuss issues arising from using beta software. To find out how to uninstall iOS beta software, read this support article —> https://support.apple.com/HT203282
If you are in the UK which has to comply with the Online Safety Act (2023) and are running the regular release of iOS software, ask Apple what to do. They have not provided us (regular users like you) with any guidance about age verification. This support article has various country telephone numbers for contacting Apple for support and service ➔ https://support.apple.com/106932 Scroll down to “Connect with live support”. If your country is not in the list, go to the “Other countries” entry at the end of the list and click on the “options” link. Not every country has telephone support, and phone numbers may only work when calling from the same country.