Using Proton always seemed like a bad idea. People come to Proton in order to deGoogle or de-big-tech but then lock themselves into their ecosystem, defeating the entire purpose.
Not mention how scummy their PR-Team, their CEO and their Business Practices are.
So many Proton sponsered content creators spread lies about how Proton Mail is supposedly E2E encrypted or how Proton VPN is supposedly a privacy and security tool.
Time and time again they have lied about how much data they have and how much they have disclosed to investigating agencies.

The only way I could ever undestand someone using Proton Mail would be to use their service but behind your own domain, such that migrating away stays easy.