Long COVID loss of smell

Some data recently in The Guardian saying that a functional septorhinoplasty for the nose, which is an operation on the nasal septum performed to improve the airway, will bring back the smell in patients who have lost their smell through the effects of COVID and long COVID. Somewhat counter intuitive though as if the blockage was causing all or part of the loss of smell, why wasn't it present before COVID? Septum blockage is caused by trauma, not COVID.