Anybody else getting timeouts and login failed errors with pop3.mailbox.org?

Using Thunderbird 145.0 (64-bit) on Arch Linux, no special firewall rules, no antivirus software to block anything, a bunch of other POP3 accounts also set up in Thunderbird working fine (GMail, GMX).

Getting almost hourly "Got an error name=pop3PasswordFailed, the server said: [AUTH] Authentication failed." errors from Thunderbird ("Login to server pop3.mailbox.org with username <USERNAME> failed." in the GUI), and sometimes "Connection to server pop3.mailbox.org timed out".

Then it works just fine for a while, then back to these intermittent errors. I've tried two different ISPs with the same result.

It's very disruptive, because the errors cause a pop-up window + system notification.

IMAP seems to work fine, as does logging into, and using, the web interface via the browser.

I've contacted support but their kneejerk reaction has been to tell me that they don't provide support on the light plan, and they closed the ticked. I've reopened it because this is not a support request, but reporting what looks like a POP3 server issue on their side - I can deal with my side.

Waiting to see if I'll get a more helpful reply, but in the meantime I'm curious if others have had the same issue.