I find it incredibly frustrating that this community specialist has marked this as solved simply because he responded. As you can see it is not resolved. There are two ways to resolve this:
1) Allow your customers to choose which default email client they are allowed to use as opposed to dictating that we must use Mail
2) Fix the display issue, this only occurs with my gSuite account, my iCloud account is perfectly fine. I've done everything that has been noted in this thread however nothing actually works. This issue was not there prior to iOS 13 so I suspect it is something within the sync/fetch setting that is causing the issue.
When I delete my accounts from mail, restart my phone and add the accounts back its perfectly fine for about an hour than it comes back. this is incredibly frustrating as I have no confidence if the Apple Mail client has properly downloaded my work email onto my device.
Can someone at Apple please properly investigate this and advise what the issue is.