Add-on version update is currently very slow. A new version would be updated within a few days of add-on review.
Now it has been over a month since the last version review but there is still some 80% of user in the old version, as seen from the statistics dashboard.
What is happening?
I’m pretty that 3.0m2 is considered a lower version number than 3.0. So, the slow uptick you’re seeing is from new users installing the add-on from the listing page, rather than auto-updates.
I think you may be right. After updating the version number to 3.1 (without changing anything else) the update rate is back to normal.