I still think it would be better to give the user freedom, and just give a warning that there are privacy risks.

There is a small important distinction.

It is because there is no proprietary e2e encryption by default exclusively while communicating with others on tuta.

E2e encryption for 99.99999% of emails is via passworded pgp that everyone else has and uses or not encrypted at all. I have tuta for years and have yet to send or recieve a single encrypted mail that is the reason that they can't have a 3rd party app outside of tuta's own advertisements I get served.

It is vendor lock in. Pure, plain, and simple.

Wouldn't be as much of a problem if their client wasn't so bad. No auto moving messages as far as I can tell, absolutely horrid search functionality where I can type the sender email word for word and it will find 0 results, and just having almost no productivity or inbox managing features in general