I’m having the same issue as this poster. And it can happen with Texts for me as well. I get the initial notification, and if there are any uncleared emails, I get notifications for all of them. If a text comes in, I get the text notification and the email notifications all over again. I’m also on a Pixel (3A).
Currently, every time I get a new text, I’m getting notifications for any uncleared email notification. Even better, I frequently get 2 notifications for every event. 1 text comes in, I get 2 notifications. Same with emails. Can someone please point me in a direction?