Screen Time shows wrong device name
Ran across a post from back in January regarding screen time showing wrong device name.
https://discussions.apple.com/thread/250998666
It doesn't look like a solution was found, but I just stumbled on the solution for me. For me, my daughter's device was showing with my son's devices name. Her devices were not appearing at all. I could update the settings, but couldn't adjust app limits.
What I did to fix this was to select "See All Activity" just below where the graphs show up. Then, in the top right corner, select "Devices". That updated the list of devices associated with my daughter and now all is fixed. Wanted to pass this along as I've been racking my brain for the last few weeks.