Error 525 SSL handshake failed with gitlab page


I have a web page hosted on GitLab Pages with a 1&1 domain backed by Cloudflare. Up to today (at least I noticed it today - last week it was definitely working) for 5 months everything has been working without any problems and I have not changed anything. Today, however, the web page keeps returning this error “Error 525 SSL handshake failed” only with the domain connected to Cloudflare.

I have tried to fix it with the various instructions found on Cloudflare and Gitlab, but nothing. Is there any error/problem on the GitLab side?