Oh that looks rough no lie, i would say its the damage of aphids, but have you checked to see if anymore are on it, when a plant goes through any kind of stress bugs pick up on that and attack, thats why some plants can have bugs and the other ones around them dont.
Also aphids can be black as well depends on where you live
For ex:
Normal aphid
View attachment 943548
And black aphids usually in their adult stage or different species:
View attachment 943549View attachment 943550
If that is the only plant, personally i would get it out the room, i know it sucks but your taking a bigger risk at keeping it in there!
You could still make butter with it and make some edibles if no bugs are on it! But if any of the other plants go through any stress the bugs will attack those plants too!
If the bugs arent on the plant its still at risk because now that plant is a target for both bugs and white powdery mildew!
I know it sucks, ive thrown away $1000's of plants in the past, but its just my opinion.
I would also grab a microscope if you dont have one 60x-100x just to make sure you dont have any RUSSET OR BROAD MITES!