Cooktop wiring (stranded alu + copper) w/ downdraft

First, thanks to all the users who take the time to respond to all the questions on here. I've learned so much over the years but this is my first post/question.

I'm wanting to replace my ~15yr old GE electric cooktop with a GE induction one. I took a peek at the current wiring in the box and I'm curious your thoughts. The previous owner of the house seemed to pull permits for any work ever completed so I can't imagine this was done incorrectly/unsafe, but I also can't be sure. My guess is that they had the appliance store do the install.

House was built in the late 80's and has stranded alu wiring coming into the junction box for the cooktop. Sounds like this common(?) for appliances like cooktops and stoves. The cooktop and downdraft has copper wire, and as you can see, everything is wire-nutted together. First question – is that okay? I've read articles ad nauseam about alu/cu but so much of it has to do with single strand aluminum wiring. There might have been some sort of ox-gard applied as there's a trace of sticky residue under the nuts.

Next question – if you look at my annotations below, the white wire from the downdraft is wire-nutted with the ground from the cooktop and circuit. Is that weird? Correct?

Everything has been like this for 15yrs but I'm not saying that makes it okay. Since the new induction cooktop has the exact same 3-wires as my current (old) one pictured below (and they're both 30a), the easy thing to do would be reinstall as it currently is (assuming it was done correctly) and coat everything in ox-gard.

Thanks for any input!