Lots of recent (meaning past 20 years or so) research shows that our gut bacteria play quite a large role in our mental functions, too.
The concept of "the self" as a single, indivisible, unchanging thing is simply not compatible with observed reality. To be alive is to be in a constant state of flux.
Is there such a thing as an eternal soul? Uh, maybe...but if there is, it's not going to be responsible for the things we typically associate with individual living people. It's not going to have your sense of humor, or your memories, or your opinions, or your math skills. We know enough about all of those things to confidently say they are not eternal.
Almost certainly, yes.
People on Mastodon are not happy about those statements, and called Proton out on it relentlessly with every post Proton made. This is Proton running away with their tail between their legs, back to platforms where they have more control and/or are already full of right-wing nutjobs.
If anyone's looking for secure email, look at tuta.com instead. The email service is very similar in terms of UX and offers better encryption. They don't offer the rest of Proton's suite, but...maybe that's a good thing? I mean, do you want to get locked into an ecosystem?