Better off with Google? Nah. You are trusting any hosted software provider you use. I'm not saying it isn't possible that Proton is a front but I doubt it. That said, this is email. No matter who is hosting it there are serious privacy issues. If you are very concerned with your communications via email you should be encrypting them yourself with GPG.
The fact that Proton's code is open source is why this was found. Read the article from the firm that reported the issue. Proton has a bug bounty (they are actively looking to fix unknown issues).
I'm not telling you that you should trust Proton but I am telling you be sus of anyone saying "Use Google".
Selfhosting is another option.
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It is but it isnt like self hosting other tools. Email is a whole other animal. I've done it.
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