It sounds harsh, but you got to get your horse to respect you. Once they’re responding well you only have to nudge them when they’re getting unresponsive. If you keep nudging they’ll just continue to get not numb.
Your horse just seems to be numb to your aids. I think you need to change up your riding routine so your horse doesn’t expect it. I think you need to use sharper spurs and you need to not ‘nudge your horse’ but give a couple of really kicks to surprise them, and a hit behind the leg at the same time.
I rode a pony exact same thing we even tried chasing other horses and nothing what we did was have her A TON A TON A TON of grain and now she is going to show her first show in the jumper ring today!
My horse tends to get really sucked back like that to - something that I find helps is serpentines, they get him to listen and pay attention to my aids, maybe try without the Spurs, they can sometimes make a horse more sucked back and less responsive
What does your coach say? This would be your best avenue for help. Have you had a vet evaluate your horse?
It really could be anything from pain, I’ll fitting tack, greeness, rider inexperience to a great many other things. Without a video it’s hard to help.
Do you mean leg/spur/crop for speed? Or turning/yielding? I think you mean speed... get her tested for Lyme disease. Lyme causes horses to be really slow, my horse and 2 other horses at the barn had it at the same time. They were super tired and didn’t want to do anything. Good luck!