SOLUTION: Sent emails showing up in Mail app Inbox (Follow Up Suggestions Turned Off)

I've been struggling with sent emails showing up in my Mail app inbox for over a year now, and it's incredibly frustrating because I like to keep a clean inbox. I'd tried everything under the sun to fix it, and nothing worked. I turned off "Follow Up Suggestions" in settings, tried booting in safe mode, all of that.

Note: this is a solution for a Gmail account, I don't know the solution if you have a different email.

Thank whoever this person on Reddit is, but this is the solution: Log into your Gmail on the web, got to settings, filters, and delete the "never send to spam" filter. This solved the issue!

Here's the reddit thread, and I've also shared an image below.