Cannot access user accounts after restore

I recently transferred a GitLab instance to another server. Everything worked fine on the first day. However, after pushing code, the respective user account is no longer accessible: You can log in, but after that no page loads (The page is just white). The only temporary solution I could find so far is to delete the affected account completely and create a new one. Until the next push everything works, but a permanent solution is not given.

Does anyone have any idea what this problem is and how I can fix it?

The instance is running on Debian 10.

I thank you for any help!

Issue probably solved. I was using Cloudflare so all the traffic went through it. GitLab just got the Cloudflare IPs, not the ones from the users. Those Cloudflare IPs were different each time. The IP-Limit per user was set to 5 in GitLab so the accounts got blocked.