🤔

I never tried it, just checked the login page (which have displayed correctly).

That said, with TOR sometimes you have to switch the routing a few times to get to an exit point that isn't banned on the sites you want to visit. Will try that with protonmail. BTW is there a tor address for protonmail? That would be something I'd expect them to have. 

 I carried out the procedure you mention before I commented here. The good news is that it's working again with TOR. 
Btw. The address looks more or less so https://mail.protonmailrmez3lotccipshtkleegeto…………………ozyd.onion 

 Great! It still doesn't work in default tor browser settings for me. Cookies, sessionstorage and localstorage are needed for it to work. Perhaps the tor mode in brave browser is the easy way, dunno I don't have brave on my computer to try it rn.