You know what would be a really easy way to confirm if Proton is sometimes requiring email verification? Just look on their own website, where they openly say they do it.
The question isn’t whether they’re doing this. It’s whether they’re actually doing it to “prevent spambots,” or if they’re employing it when they need more info to track who’s signing up.
There’s really not much you can do. There’s just too many cameras in the public spaces. If any government official wants to see who’s visited an abortion clinic, they can just have the local traffic camera company tell them.
We need to ban the government getting around the 4th amendment by partnering with private companies.