I have many of the same questions you all have posed here. In my FindMy app, I see items for myself and three other family members. Interestingly, I see some items like AirPods for people I don't know. I am assuming that these items were lost AirPods that someone else found and decided to keep. I also see some Macs and an iPad I got from my old job, that I no longer possess. All told, I see 22 devices and 6 AirTags. Can I choose to forget some of these items so that do not count against my limit?
Update: Clicking in the information i will let you remove an item.
P.S. Interestingly, all of these rogue items are NOT sharing location information. And even for items I am NOT the principal owner, I can remove them from my FindMy app, alert me when found, and remotely wipe them‽‽‽ Who knew?
P.P.S. After studying the various items in our family's home, even if someone connects to another person's item such as AirPods, it appears even if that item is not sharing information. I suspect if there is a hard limit of 32 items per person, it's only ones that are sharing location information or perhaps the 32 most recent items?