Not as bad as yours, but MySQL and also blocking prod table: on my first job after graduate, I once run a delete commands on about 20 rows on a quite large table (maybe 500M+ rows), but was causing deadlock because of gap lock, it has been 6 years so I don't really remember the details.

I was not expert but knew about MySQL optimization at that time, but it looks like sometime you just do things and not think through.

15 minutes later, sysad team PM me and ask WTF am I doing, and I realized what happen.