Leg IK Bones seem something wrong when I import on the game

I’m new to making a Game using Unity 3D

So I was making a game where my camera looks at my character while it moves. I have imported some animations like Walking, Idle and Running. I tried to make use of those animations to my characters but when I tested out the Walking animation and the Running animation something is not quite right on the IK Bone of my character, it’s located at below the LowerLeg Bone. I don’t know why but I see it weird because both the mesh and the bone is having stretched. I can’t explain how it is but I’ll just send some screenshots here.

Walking Animation

Running Animation

I don’t know why this thing showed up when I import it on Unity, when I was animating there’s nothing issue about this, I use Blender to make 3D models and animate them.

I think you need to check the weight painting on the model but I’m not sure.