my animation glitches when i add more keyframes

I have created a few animations in unity and in one of them everything was going smooth up until a point where if I add any more key frames to the animation it breaks the animation and glitches the player out during runtime just by having the animation in the animator even if the animation is not played. I do not have an excessive amount of key frames and it is only about 20 seconds long I'm wondering how to fix this bug please help