Yes, the activity counter has been broken for a long time. The number plummeted just about instantly by at least half when the last forum reskin happened a few years ago.
A friend and I have a hypothesis on why that's the case, and the number should be higher than it is as far as we can tell. Maybe some day it will be fixed (or the exact algorithm will be shared so I can tell if the hypothesis we came up with is right or not). In the meantime, I've not paid too much consideration to what number it shows.
08-Jul-2018 16:16:56