I had a coworker who had a 2,000 line PR that took me
3 days to review, it was like code breaking. Custom abstractions upon custom abstractions, abstractions in custom imported utilities for a one-liner that was only used once. Basically, instead of writing the code, he made code that generated the code that was needed, once the program was running. Dear Lord. Like somehow this monstrosity was good because instead of creating the feature, he built tooling to make many identical features whenever we want! Except nothing can be different, if it's different we need to rewrite the whole thing.
Every 4 hours or so I would ask my boss if I really had to do it. He told me to just keep going, I think he was building a case for letting him go. I still only made like 10 comments, needless to say they weren't taken well. What a nightmare.
Tangential to this whole thread, but guys like that, every day he worked took two days for other devs to fix/undo his work. Took my company a few years to catch on, he was a senior dev and also good at talking himself up. I would have paid him the same salary to go sit on a beach somewhere and enjoy himself instead of touching the code, we'd all have been happier. In fact the world would be a better place, because now he is presumably working somewhere else doing the same things.