Holy crap! That's got to be in the top 5 worst I've ever seen. Either a cat peed on it, or you've had a bad terminal seal leak. Long shot, maybe the system heavily overcharging the battery, forcing out boiled corrosives. This is a '19(?) and you've had to replace the battery already? Makes me wonder. Stating the obvious, you're going to need a new terminal and maybe a battery. I think I'd have the charging system checked. The felt washers help a little but won't cure a major acid leak.