So Proton users who like to connect via Tor onion services have been faced with a choice of either staying on the old version of ProtonMail, or giving up on connecting via a Tor onion service. It definitely leaves the impression that they don't care much about Tor anymore, or that it's at best an afterthought for them.

https://protonmailrmez3lotccipshtkleegetolb73fuirgj7r4o4vfu7... is the URL that people should be using with Tor if they are concerned with being traced.

Using Tor to access a regular web site, ie: through an exit node, is (nearly) no different than using a proxy. Just assume all exit nodes are "naughty" and do your thing accordingly.