Still get email in background with Push OFF and Fetch MANUAL

Hello Phil2307.

Welcome to Apple Support Communities.

If I'm understanding correctly, your email is still being pushed to your iPhone even though you have Mail Fetch set to Manually. I will be glad to assist. You have performed some great trouble shooting thus far. Next, let's remove and re-add your mail account to see if that helps. See below:

If you can’t send or receive emails on your iPhone, iPad, or iPod touch

"Remove your email account and set it up again

1. On your computer, sign in to your email provider’s website. Make sure that all of your email is there or make sure that your email is saved somewhere other than your iOS device.
2. On your iOS device, go to Settings > Passwords & Accounts.
3. Tap the email account that you want to remove.
4. Tap Delete Account.
5. Add your account again.

"

Cheers.

Use the account settings to disable the use of the accounts, until and unless you need those? Which is admittedly immensely ugly. Or mask the arrival of the data by turning off the app badge, and turning off the notifications. Otherwise, I suspect you're here headed toward providing feedback to Apple about this.