A lot of us are in tech and we come across these problems and just troubleshoot our way around them and don't really think about them, so I figured a "case study" might be helpful. ~~Image unrelated.~~
Anyway, yesterday I tried making an alt account on lemmy.world. When last we left the situation, I had been notified that my registration application had been denied, but I'd been asked to confirm my email and https://lemmy.world/u/sergio had been created. A couple helpful commenters suggested my account might still be under review.
- Today I tried logging in again. But when I entered my username and password, I got a popup that said "incorrect login credentials". Maybe I needed to verify my email again? I went to my email, clicked the "verify your email" link, and just got a page with text that said "verify email" and nothing else. Maybe it didn't like me using my username to log in? So I tried logging in with my EMAIL and my password, and still got that "incorrect login credentials".
- Maybe something's wrong with my password? I'm using a password manager but OK, let's just try changing my password. I clicked on the "forgot email" link on the login page. I entered my email address and clicked "reset password"... and nothing happens. No feedback, and I don't get an email. (10 minutes so far).
- maybe I should check https://lemmy.world/u/sergio ? Hey, that's no longer there, I just get an error! I check the user page of another lemmy.world user and it works, so it's not a server problem. Maybe my application really was denied? Was it really reviewed? What do I do now?
(my intuition is to try again with a different username, email address, computer, and browser from a different location at a different time of day...)

it was just the purges and the emails being broken at the time. once we discovered the breakage we immediately started working on fixing it. the problem was that we initially missed that it broke.