There are a couple issues I'm aware of that tend to make people wary of Proton.
First is Andy Yen's open support of fascists. Which you mentioned in your post. I know that he has tried to walk back his comments and claim they aren't political, but anyone claiming the GOP is anything other than fascists and oligarchs is either too stupid to trust, or dangerous because their beliefs are aligned with those fascists.
Second is that Proton continues to expand their suite of services and are trying to get people to buy into all of it, much the same way that people bought into the google suite. This centralizes many services, which is problematic if the company makes changes that do not align with the users wants and needs. So many people push to avoid this. Centralization in general opens users up to enshittification that is difficult to extract yourself from.
There may be more, but that is what I'm tracking. And it's why I ended my subscription with them, and moved most of my things away from Proton mail.

