I don't remember exactly which sites, but I run into the problem every so often with a handful where I'm prompted to change my password according to vague guidelines that say I usually need special characters, without saying which ones it accepts.

I change my password with something randomly generated by my password manager, and the site accepts it, and as far as I know I'm good to go. Then next time I try to log into the website, it doesn't accept the password it previously (falsely) accepted before, and I have to reset it again and play the guessing game of what special character it didn't like. Madness.