rshadow1980
Proton has been... unreliable... about actually open-sourcing their apps, and keeping their open-sourced files up to date so people can build the apps themselves to double-check Proton and make sure they aren't pulling any funny business.
They also have been caught pinging google... Though to be fair, it is for reasons and within contexts I don't claim to understand, but that looks like a red flag to me.
Maybe these errors are good-faith mistakes, maybe they aren't. I personally am migrating to Tuta email and calendar.
I intend to use syncthing-fork for the rare occasions I need to move stuff between profiles, and for backups, when I get around to all that.