How do protonDB contributors figure out custom launch options ?

Every time I check a game on ProtonDB, I see suggested custom launch options. I always wonder: How do people figure these out?

My best guess is that they check the Proton documentation and then experiment through trial and error. Or do game developers ever provide these options themselves?

Side note: I’ve noticed that many of these contributions suggest out-of-date or deprecated options. It makes me wish there was a way to up/downvote these suggestions.