Why is the Mail app mixing up email headers and content on iPhone?

This is not the first time and it’s very annoying that the best phone in the world has a Mail app that can make such incredible errors.

I’ll see a title that reads, for example, “Your Schwab account has a new deposit”. When I open the email, the body of it is from American Airlines!

I then check another email app, for example Yahoo Mail, and there are no mixups. I also check on my desktop pc and there are no mixups.

So the problem is with the app. Apple iPhone’s native Mail app!

Any ideas, besides deleting and reinstalling Mail accounts? Is there no other way to fix this issue? I have deleted and reinstalled Mail accounts in the past. It fixes the issue. But 6 months later it happens again. I know, time to buy a new iPhone!

Seriously, any help would be much appreciated! Thank you!

[Re-Titled by Moderator]