Figure out if you're sure it was the copper and not something else like overwatering or a light change. Plants brown for about a hundred reasons, and blaming the $3 mister is the easiest one to point at. Even if there was residue in there, a quick rinse would've handled it before it did real damage. I've got old sprayers with god knows what in them and my plants are fine because I don't let them sit with stale water. You probably just had two sick ferns already and the timing lined up.

Yikes, those things are just overpriced rot machines.

Rolling back to a checkpoint from last Tuesday is wild, that's like a week of progress just gone in one swoop. My buddy and I lost about two hours on the same swamp area, and we both just stared at the screen in total silence. Devs really shipped this thinking it was fine, that's embarrassing.