DeLorean is 304 Stainless. Cyber truck is 30? stainless. As in Tesla doesn't want to say, which is why they write it "30X".
given how hard the steel is purported to be, it's likely a variant of 304N, instead of 304 or 304L. (basic stainless like in commercial kitchen equipment and 18/10 stainless, like in high end cooking pans). 304N is harder to work with cold due to it's hardness and gets harder when worked, both properties Tesla has reported as belonging to the cybertruck's steel. 304N is considered a marine grade stainless steel.
There have been a lot of developments in stainless steel production in the 40ish years since the DeLorean came out, so I highly doubt it's the same steel.
Maybe, and likely, given all the other cuts they made, but as far as I know it's not actually known, which is frustrating. That said the article calls it an SUV and isn't exactly riddles with facts, so.
The pictures from the cybertruckowners forum show something on the surface causing discoloration, like road grime or dust disintegrating in the rain, not like rust forming on metal. I've restored a few rusty stainless kitchen knives in my day, absolutely abused ones, and even cheap stainless doesn't rust like that, that fast. I'd expect rust pin spots that bad on a chipped paint job over mild steel, on stainless that's had iron embedded in it (like from scrubbing a sink with steel wool, or on chemically altered steel (like filling a stainless sink with bleach and putting an iron pan in the same sink for a while).