[orlp]

Technical nitpick purely on the wording of the title: the pentesters declared that "no important security issues were found during the pentest". Unfortunately in our current world that's about as good as you're going to get for a large software system, but that does not necessarily mean that Proton is secure. There could still be undiscovered vulnerabilities.

[Macha]

Yeah, it's a bit like when someone says their relative's doctor said their cancer was cured. This is basically an impossible statement for a doctor to make to medical standards which is why the best you're going to get from a doctor is a statement that someone is in remission or the latest scan did not find cancer cells.

When someone makes a stronger claim you're left wondering if it's the original source or the messenger that's after oversimplifying the situation and it looks bad for one or the other.