Mastodon “Trending” is just stuff that wasn’t talked about, suddenly being talked about. That’s why constantly popular things don’t appear on Trending, but things like “BigBoobFridayWhatever” (or equivalent) gets trending (people don’t use the hashtag for a week, and everyone use it for that day). I see how they thought it’s perfect for world-wide events, but it just end-up being a bunch of “weekly” stuff.