You most likely have a bad brake caliper on the side that it pulls to.
Time for new brakes or adjustment.
brakes
prob caliper issues and/or alignment
Remove the calipers and the disk will pull right off
You have an alignment problem. Possible problems that help with this are tires, brakes.
Long pull brakes have a longer cable pull distance compared to short pull brakes. This affects the amount of force needed to apply the brakes and the overall braking power. Long pull brakes provide more leverage and are better suited for larger tires or fenders, while short pull brakes are more responsive and better for smaller tires. The choice between the two depends on the specific needs and preferences of the rider.
air still in lines. rebleed
Alignment, dragging brakes, low air pressure in one tire.
Sounds like problem with brakes. Pull the wheel and you should see the problem.
You have a problem with the brakes, have a mechanic check it out soon before you have no brakes.
when you pull back on the reins.
pull over to the right side, down shift and look for the safest escape route.