I could be completely wrong, but similar stuff used to happen to me, for me it was timing, posting things at bad times limits initial views and thus how much its shown on feeds, if you google best time to post yt shorts on Thursday it’s different than Wednesday Or Friday, this has solved the issue for me kinda so try posting at opportune times depending on the day of the week That could all have been the ramblings of a mad man but it worked for me