Using both Gmail App and iOS Mail App on iPhone - deleting in one app doesn't delete in other

I have several email addresses. I have all of them in my iOS Mail app on my iPhone. One of my email addresses is a Gmail account. I have that in my iOS Mail app, but I also have the Gmail app for that particular address. I use both apps to manage that email account. Don't ask me why.

Here is what I would like to happen: When deleting a specific email from my Gmail account on the iOS Mail app, I would like it to be deleted in the Gmail app as well. Conversely, when I delete an email in my Gmail app, I would like it to be deleted in the iOS Mail app also.

I would think that because the emails in my Gmail account come from one server, it would do what I want, just like emails do with a POP3 email server. But instead, if I delete an email in one of the apps, it remains in the other app, so I have to manually delete the same email twice.

I have looked for an answer to this on this community, but it seems when people have asked this question, the answers they are given are not really helpful. Can anyone help me with this problem? Or am I doomed to have to delete everything twice?