Plant Problems with pictures.

I just noticed this starting to happen a couple days ago, idk what the issue is. I have them outdoors, but somtimes I bring them inside when its extremly cloudy and put them under lights. I dont feed with anything, just give them water.
Here is 3 pictures of 3 differnt plants, I am very new so I dont know what is causing it.




Is this problem very serious? Or will they recover on there own what do you guys think? Any help is greatly greatly appreciated.

You see any more slime trails like that one leaf?
Maybe snails or slugs, but something is eating it.

the first picture looks like some sort of bug either aphids or something similar. id get some neem oil for it. pretty cheap and effective

the second one looks like n def or cal mag def.

the third one i have never seen before and looks pretty crazy

the last pic looks like a leafminer

u got a bad case of leaf miner. all u can do is remove the infected leaves and dispose in a trash can. spraying will not help, as the insects live between the layers of the leaf. start spraying with neem oil weekly. GL

id burn the infected leaves