Misguided unwanted action in between 2 keyframes. Help?

With an rigged character, i animate it. But, in between the 2 inserted keyframes, there is unwanted misguided action. Something like the character’s leg streched upwards away while there’s no keyframed because it is in between the 2 keyframes.

I’ve checked the action editor, graph editor… but didn’t found the solution. :frowning:
How to fix it?