This! And more: Proton is likely a honeypot. Investigate Andy Yen. He was not at CERN, when Protonmail started.
Same pattern as the Signal messenger and Moxie Marlinespike.
DYOR & Don't trust. Verify!
Discussion
Proton is extremely divisive in terms of the privacy community from what I've been reading. I don't think it's a honeypot, as they've been vetted by independent (non-blackamailed) third-parties before, especially with their VPN from what I'm aware of.
Especially since all of Proton's stuff is under AGPL-3, that might be the reason for the divide?