Are they disconnecting, or is it like some inputs don't get recognised? I had issues in the past but figured out it was my own fault. In my previous house I had the Switch docked partially behind the TV, and I noticed if I was ever sitting with my feet on top of the chair and held my left hand beside my left leg the left Joy-Con wouldn't properly send inputs, basically because I was blocking the signal from actually getting to the Switch. I'd look into that, just in case it's something similar happening to you. It happens occasionally with my pro controller too depending on how I'm sitting, but it's not as bad as with the Joy-Cons.