iOS E-mail stuck in « All Inboxes » [duplicate]

In the iOS Mail app, there are 4 emails in the "All Inboxes" section. Those 4 emails are NOT in the actual inbox on Gmail.

I thought, oh well I don't mind deleting them entirely since they're just newsletters. I deleted them directly on gmail, but they still appeared in iOS. So I tried deleting them via iOS and ... they keep coming back!

Even stranger, the 4 emails ONLY appear in "All Inboxes", they don't appear in any of the sub-account inboxes.

So, I disabled "Mail" in my gmail account. They're still here! I no longer have a "gmail" sub-account, but those 4 emails are still in All Inboxes. I tried to quit the app a few times, restart the phone. Still here...

When I tap on one of those messages, I get a black screen (dark mode), no errors.

It seems there was an inconsistent database attached to the account.

Removing the entire account from “Password & Accounts” removed the ghost emails.