‘Report Update’ notification that gives an error when clicked

These don’t have a sender, just a notification that says Report Update. When I click on it I’m taken to a completely blank page that just says ‘not found’.

Am I supposed to be getting these? I’ve never got a notification like this before so I’m not sure what it’s supposed to look like if it loads.

Not sure if this is a Piefed issue generally or a Blahaj server issue.