moveposition() not working when slowing down the game!,rigidbody.moveposition not working when slowing down the game

I use rigidbody.moveposition() to move the characters (using other things like transform.translate() cause colliders to not work) and it works nicely.

but when I slow down the game with timescale it doesn't work properly, the character stops at a specific position (like, for 0.4 seconds) and then suddenly moves a bit forward and so on.

I understand moveposition() is not designed for (correct me if I'm wrong) smooth movement but it does work pretty well at normal speed, so is there a way to call fixedupdate() more frequently when the game is slowed down? and if there is, how to calculate the value? (let's say I'm setting the timescale to 0.3f)

or if there is better ways to overcome this, I would be glad to hear