If once it starts moving, it's tight, then I would guess it is a worn section in the middle of the rack. The center of the rack gets beat up the most. If it's loose the entire time even after it starts moving, then it could be a number of things and the tightening suggestion above is a good place to start.
If it is tight once it starts moving and you tighten that adjuster, you'll then find that its fine when the wheel is straight but extremely hard to turn the wheel once you get past that worn section. You'd want a steering unit if that's the case.
[This message has been edited by reinhart (edited 02-03-2021).]