I've learned to click "recent discussions" so I don't miss anything - In the past couple of weeks, I've noticed a lot of very old posts coming up - today was one from 2016 and the other day from 2013??? I assume it is because people are searching certain terms? That doesn't explain a random painting thread coming up and comments about how great it is (or whatever) when it is so old - plus, these people don't seem to be active otherwise - not noticing current events?
Perhaps the settings are different for different computers, MAC, phones etc... I never noticed it happening as much as recently.