iPhone 12 'Cannot verify server identity'

I have the new IPhone 12 I got recently and this has been happening with my old XR too but get constantly spammed with “Cannot verify server identity” the identity of “imap.gmail.com” its super annoying and rediculous .it has to do something with the wifi but the same problem does not happen on my brother IPhone 12 which is on same wifi. What setting can I do to stop this annoying message. I can’t even press trust on whatever message comes up there no option to get rid of this annoying message. This happens at home wifi and random wifi outside .

[Re-Titled by Moderator]