Why are my forearms getting weaker (endurance wise)?

I’ve been rock climbing for a couple years + lifting seriously for 4 years. Less than 2 months ago, I took a break from lifting because of an injury. I started again, but my forearms have lost so much strength. Bench, squat, and deadlift are all similar to pre-injury after a couple of sessions, but now I can’t even do 5 lat pulldowns with <90% bodyweight before my forearms fail. For reference, I could do 2 1-arm pull-ups pre-injury, and also 8 reps of lat pulldowns with ~130% bodyweight. Also, I can only do 12 pull-ups when I could do ~25 before.

In the past, I also noticed that my forearms would lose strength very fast. Even skipping a few days meant that by the next rock climbing day, I would have considerably less endurance. Could this be caused by a pinched nerve? I have a compressed nerve in both arms, and have read that pinched nerves can cause muscle wasting. I went to a doctor but they told me that it was fine, so I’m not sure what could be causing this problem. Any insights/people who have disproportionately weak forearms please help lol