Animation mismatch

Hey there

1. This could come from Unity compressing your animation curves. The further down in the hierarchy a bone is, the more rotation errors from this compression will accumulate. Have a look at your import settings. Is the bug still there if you set that to no compression?

1. If this doesn't help, the issue is more likely in the export from your 3D program. Are you baking the keyframes before exporting? If not, try if it helps.