I don't want emails to flag notifications as read

Hello.

I’ve been missing notifications for a long time and I was not understanding why. Turns out that, when you open an email of a notification that email flags the notification as read.
This is a behaviour I didn’t asked for, that I don’t like and that I want to opt out from.

How can I deactivate this read status sync?

Change the setting in Gmail general setting.

Can you give me more details on how?
Thanks.