Yeah, you see where this is going. The prod dump finished in time and shortly before leaving work I started importing the data. Then I sat around for a while before I realized I had forgotten about that additional "use the test environment" parameter -- and now I was importing a several hours old dump into the production database while the daily production run was running. I had to call company execs and explain the catastrophe to them, who in turn had to call in the vendor that sold us the system. Those were some pretty scary hours for a 20 yr old kid. Luckily it was just a matter of aborting the production run, reload the prod dump and then reschedule the production run for the day.
The next day I had to start my day at the vendor's place to get some shaming, but also a good piece of advice - "always say destructive things out loud before doing them". Then they continued to tell me stories of people they had worked with who really messed things up, and we all had some good, evil laughs.
Mistakes build experience, and hard learned lessons even more so. You now have a pretty good conversation starter to put on your CV. Personally I'd rather hire someone who was a "removal" specialist over someone who hadn't learned the skill yet. :)
I believe both GitLab and the community in general will come out stronger from this incident. Thank you all for being so transparent about it.