If I had to guess, n others isn't the number of people who followed you since you last checked your notifications, but rather the number of people who followed you since some cache was cleared.
So your 8 is the 2 new ones, plus 6 others that you had already checked the notification for.
Since dev.to is now open source, I imagine going through the code and figuring out what exactly is going on there would be a fun learning exercise.
There's also the chance that some other 6 folks have unfollowed you between this moment and the last time you saw a notification before this.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.