dnd 5e – How can I modify this crouched rule to balance it?

My ranger uses a light crossbow, and after a few sessions, he constantly tells me to crouch before attacking and before his turn ends.

Disadvantage in all remote attacks against the crouching character, but unlike those in a prone position, they can get up and continue moving without movement penalty.

The crouching character also spends 1 extra foot of movement per foot moved.

After a few sessions, I think having all my attacks prepared against him was put at a disadvantage, and the attacks on my next turn are also ridiculous.

How should I modify this crouching rule so that it gives some kind of mechanical advantage, but not big enough so that players can abuse it?