luna1483 Thanks for sending the reproduction project.
Strangely re-exporting your provided Spine project as .skel.bytes file, even with Animation clean up enabled, and copying it over the asset in the Unity reproduction project already resolved the issue on our side. What's strange is that the .skel.bytes file shows Spine version number 4.1.20, which would be the same latest Spine Editor version that we just re-exported the asset with.
Could you please have a try whether copying our exported .skel.bytes file (we just sent it via email) over your reproduction Unity project and let us know if this file displays properly on your end?