Minor correction: The interminable "trying to load something" indication is not a spinning icon; it's that the empty rows of different colors "pulse".
problem going to tournaments from their notifications
Same here, for my last two tournaments, joining from the notification link hung indefinitely and I was only able to join from the club’s event page. For me, this was before and/or right at the same time as the sidebar change. I don’t seem to get notifications now and can’t say if the issue continues.
On desktop, for the past week or so, whenever I click on one of the notifications (I mean the ones that appear if you click on the bell icon at the bottom of the left sidebar) that are like "Tournament blah blah blah starting in 37 minutes", I get taken to a page with a blank board and an essentially blank right sidebar (where info on the tournament would usually be). I say "essentially blank" because there are empty rows of different colors, and a spinning icon indicating that it's trying to load something. In my experience, waiting for it to load something is futile.
I *can* get to a (working) tournament page by going to the club that's hosting it and accessing it through the schedule posted there.