I somehow broke my project file

Hey there!

I somehow broke my file it seems, does anyone have any idea what’s going on there?

https://streamable.com/ywrbaw

When I append a model and move it around, some parts just stay behind suddenly

I have other models in the same .blend file already and I could pose those just fine so I must have changed something somehow without realizing

When I open the model file itself I can just move it around without any issues, so the problem is with my project somehow

https://drive.google.com/file/d/1RBgvQFqcuuHONLAzXbtqeC5moqZGgbPa/view?usp=sharing

^this is the broken project

And here’s the model I try adding

mediafire . com/file/i0nrgdxnbwcbdsn/RainbowDash_1-1.zip/file

Any clue what’s going on?