Turn off new follow up function in IOS mail

I cannot turn off this infuriating follow-up feature. It’s been annoying me for almost 2yrs since it was launched.

Unchecking the follow-up setting makes no difference.

If there is a “?” in the outgoing message a follow-up email lands in my inbox about 10 days later.

And before anyone suggests it - YES I have this option turned off (both in phone and mac) and YES I have uninstalled Mail and reinstalled.

It is SOOOO INFURIATING- Apple when will you ever fix this awful feature! Or, better still, just get rid of the feature, it’s utterly pointless anyway.