Apple Mail filters my Mail unintentionally

Ever since the most recent major iOS update, I’ve had an issue with Apple Mail on my iPhone 14 Pro. Unfortunately, the problem wasn’t fixed with the update to version 26.1 either.

I have several different email accounts from various providers and organisations — Gmail, private domains, Microsoft accounts, etc.

When I open the Mail app on my iPhone, it only takes a few seconds before the email I’m viewing disappears, or the entire inbox view vanishes.

If I tap the filter button twice, the message or inbox overview reappears. This can also happen while I’m in the middle of reading an email, which is quite frustrating, and I’m therefore considering switching to another mail app — although I’d prefer to keep using Apple Mail if I can find a solution.

Has anyone else experienced something similar — and more importantly, is there a fix?

Turning the phone off and restarting it has been tried several times, unfortunately without any success.