On reddthat, we got this notice in an announcement back in March 2025:

Age Restriction

Effective immediately everyone on Reddthat needs to be 18 years old and futher interaction on the platform confirms you are over the age of 18 and agree with these terms.

If you are under the age of 18 you will need to delete your account under Settings

This has also been outlined in our signup form that has been updated around the start of February.