They were allowed to sell to china, just not their top models. It was widely known that china acquired those indirectly.
What changed is the publicity about the affair. So this is about the affair.
It's widely known that luxury cars stolen in the west end up shipped to the UAE, where they're resold, frequently to Russian customers.
So for example, a stolen Porsche could end up being driven by a Russian oligarch.
Porsche is not on the hook for this. The car was stolen by a third party.
If a Porsche exec instead had sex with the thief and tossed them the keys to a brand new 911, then they might be on the hook for violating sanctions.
Or the publicity about the affair put a brighter light on the thing that was already "widely known" and increased the need for a response.