3D animation problem

I make most of the 3D animations in my game by using Source Filmmaker and porting it into Unity by Blender
now it worked well for all the animations i tried to port until today when i tried to import my running animation.
whenever I make the running animation play, it plays the animation but makes the right arm go crazy for some reason
when i inspect the animation on the model in the view model everything looks fine however when I try to make it play as I run the project some parts of the animation looks messed up
I assume it has something to do with Unity's animation curve system .
I'm sort of new to Unity so thought it would be a good idea to come here and ask for him from people who are more expirieced with animations in Unity
if anybody knows how to disable curve or disable any side effects on the animation please help!

 

I had a similar issue before. Also using Blender and with a run clip. I got it fixed by making my rig start in a T-pose before exporting to Unity (I was using A-poses).

If you used an older build version, like pre 2019 , you might not encounter this issue.