I'm not sure if this is a universal experience, but I've noticed that every now and again I will get notifications about users following me whom I have already been notified about in the past. I.e., I keep getting notifications that the same people are following me.

I'm not sure if this is from users unfollowing me due to disinterest and then later following me again, or if they're going about spamming follow and then unfollow to bring attention to their account. Or maybe it's a glitch, idk.

It's not really an issue, I just found it interesting.

I would guess it is someone failing to click the "View all by..." button in the top right of an itch page. I find myself missing it now and again leading to an unfollow. In particular this happens when the "View all by..." button doesn't even exist. Someone have only a single asset upload, so the option to view their other asset is then replaced by the follow or unfollow button (however this clearly isn't the case for you).