20 months is a long time. Typically after 12 months you should be back to 100%

Stiffness can last longer if your hip surgery was a posterior approach compared to anterior or anterolateral approaches.

If stiffness is persistent typically a muscle imbalance, meaning muscles around the hip differ in strength or tension.

Physical therapy should be able to help strengthen things or loosen things up.

General activity level and body makeup can factor into it as well.