You have around 8 volumes of over 13 differents assets. Each volume of an asset you registered as a project in itch.io, so you easily have over 104 projects, it's no wonder this will spam all of your followers.
I don't see a point of uploading small packs of assets (except in a very specific scenarios) specially as different projects. I suggest you group them in 5 or 6 projects at maximum and keep your updates in each project, you can still do smaller updates as devlogs, nevertheless you should consider uploading in bigger packs after all I guess you only want to inform your followers about new updates if they are meaningful in the eyes of your followers, i.e., as a follower I would be interested in knowing about a release of a big pack of several assets, but I'd consider spam if you notice me about a release of a 1/8th of a pack of a single type of asset.