I am 28 years old and have been working out for more than 10 years, suddenly I lost strength in all my lifts and am unable to progress for a year now.
My training routine is as follows
Monday: 5 sets of weighted pull ups, 5 sets of dragon flags
Wednesday: 5 sets of weighted dips, Iron cross on rings, 3 sets of Russian dips
Friday: 5 sets of weighted pistol squats, 1 set of single arm push ups, 3 sets of partial reps of harop curls
To give you an idea of how much strength I lost, I was able to do about 12 reps with ease in one arm push ups and now I can barely do 2, what is more, for a year now I am seeing no progress at all on any of my exercises and also I have gained a lot of fat and never in my entire life I have been fat, people used to make fun of me about how skinny I was, and me gaining fat came as a surprise.
Also, it's worth mentioning that this drop in physical fitness happened during the lockdown, I don't know if this has anything to do with it.
So I want to ask, what are the possible reasons something like this could happen? I realize it's hard to tell exactly what happened, but I am not looking for a specific answer but rather a list a reasons that could cause this.