Hello, I read that it is a problem when a horse's training require high speed or an important effort , so for a racehorse or a show horse it is definitely a problem.
I found some good and detailed informations here if you want to go further :) : https://www.equitom.be/en/medical-services/surgery/keeloperaties/
It depends on how much you do. For the most part, it's fine and doesn't really affect the horse. Horses in high performance, particular in racing or endurance, it may present more of a problem. If it is a problem, and your horse is suffering from exercise intolerance because of it, there are operations out there that have generally a good prognosis.