I use mailbox.org, my 2 points for it were:

• it has IMAP support, so I can use whatever client I like
• for “normal” people it doesn’t sound very strange.

Obviously ArchWiki has a guide where to look for information: https://wiki.archlinux.org/title/General_troubleshooting

Look for errors in logs, a lot of things can do that.

Update discord, there was a news about that recently: https://archlinux.org/news/glibc-241-corrupting-discord-installation/