What’s the cause for this?

My guess es overwatering because the leaves feel funny like soft. Compared the the other plant which us doing fine I used the same amount of water. I don’t think it’s to much nutrients because I only fed them twice a little bit and it’s at least a 2 weeks ago that I fed. I am thinking to give them NPK 2-6-4 and just in case I got cal mag on my hand because I first thought it’s a cal or mag deficiency. But what yet you guys thinking?