A very abnormal event for one of my repos

I created a new repo on Gitlab 5 days, today I received an email from Gitlab telling me that “a merge request can’t be merged due to conflict”, I’m the only person on this repo and it’s a private one
I found more than 29 issues created 6 months ago _ I only created repo 5 days ago :D_ and I found more than 30 other branches.
All new branches, issues, merge requests appeared to be created by me but 6 months ago.
I can’t share the repo or the created list of issues.
I really need help from the Gitlab support team to understand what’s happening.