Email validation keeps being a problem because the rules keep changing. The assumption that .pizza is not a valid TLD was valid before, but is not valid anymore, but not everyone has updated themselves to understand these new rules.

It could also be that they see a lot of fraud from people using non-traditional TLDs (basically the gTLDs) so they block those, but serve some generic error that looks like their email is not actually valid.

But then email validation has basically always been an issue. The only real way of validating emails is to send an actual email to specified address and ask the user to input something that that email contains, but that adds a lot of work than some simple regex.

I also used to use a uncommon gTLD, but then we're not "normal internet users", at this point at least, maybe in the future. Best work-around I came up with is having a traditional TLD that I can use when the system doesn't work with the email I usually use. I think this is the best thing you can do moving forward, because Sony is not the only ones fucking this up, there are plenty of services that don't accept your email if you use something like .pizza, .app or any other common gTLD.

Edit: I should clarify. "Rules" is referring to regex rules, for the ones who are engaging in the fruitless endeavour of trying to validate emails with regex, not the "rules" as the specifications for what emails addresses are actually valid. I restate what I said elsewhere: only proper way to validate emails is by sending a email to the address and make the user input some data you sent in said email. Anything else is bound to not work for X% of users.