When I get a notification in my inbox in the last few days, I've seen that it won't clear to "read" status after, and the badge will stay on it, unless I select "mark all as read". Notice in the screenshot below I have one not grayed out; it won't turn gray (and remove the badge) even if I click on it, even across multiple sites visited. This occurs even with extensions turned off, so I don't believe it's ad-blocker related.
Mac OS 12.4 (Monterrey), Safari 15.5
