As a side note, DBeaver actually asks for confirmation if it thinks you are about to do something wonky. I think it's quite telling just how common this mistake is. We've all been there
I did something like that once, I wasn't very good at SQL but I needed some data, so I logged in into the production database and run my SELECT queries, I didn't change anything so everything was good, or so I thought.
I created a cross product over tables with millions of entries and when it didn't respond I thought it was odd but it was time to go home anyway. On the way home they called me and asked what I did. They had to restart the DB server because once the cache timed out one application after another started failing.
Ouch. Gotta wrap those deletes in a transaction and look before it rolls forward.
Lessons learned. Time to see if the backups actually have any data on them.
Good companies wouldn't fire someone for this because:
There should be processes in place to prevent this, or recover from this, anyway. It's a team/department failure and you would just be the straw that broke the camel's back.
They now know you've experienced this and will hopefully know to never do it again. Bringing in someone else could just reintroduce the issue.
I did quite a few bad things like that early on. Now I never type UPDATE or DELETE without first doing a SELECT and WHERE. It's easy to convert to a DELETE and UPDATEs tend to effect only a few fields at a time so the extra effort is worth the peace of mind. It's a good habit to form, I can't even think of the last time I did anything horrible.