Hello,
After importing the animations from Mixamo, running them on the model results in this weird behavior:
How do the animations look when run in the game itself (not the animation preview)?
Make sure that the animations you use for the Knight were downloaded with the Knight selected as the model within Mixamo (Mixamo often has different skeletons/tolerances for different characters).
If it’s working ok in the game itself (as opposed to the preview) I wouldn’t worry too much about it.
This is not going to fix your problem but as an aside; your animation seems to have root motion turned on. When you export animations from mixamo (at least for this course) you want to check the ‘In Place’ box before exporting. Also turn off root motion on the animator controller.