In my opinion sending weapons would mean a step-up in the conflict, where USA will feel the need to respond, etc.
While it would be an unwelcome development, the response from the US, EU and others is most likely to be in the area of trade.
That response is unlikely to include Tesla cars from China, as Tesla is a US company.
To some extent there are already trade hostilities between the US and China, with the IRA being one of the trade actions.
The only reason why China hasn't provided Russia with more open help so far is fear of a trade backlash. IMO the other fear China has is, Russia losing,
When the Chinese say they want a negotiated end to the war ASAP, I think they are serious, and would like to make that happen. But there is no deal Russia and Ukraine are likely to agree on.
US leaks about China providing weapons are designed to prevent China supplying weapons. China knows trying to secretly provide weapons will probably be exposed.
Assuming China did provide weapons, then trade sanctions would probably target as close as possible to the Chinese industries providing assistance.
The big problem with starting wars, is no one knows how a war is going to end, and while it is on going, there is always a risk of more parties being drawn into the conflict. So I would not entirely rule out bad outcomes which might affect Tesla, but so far not much of significance has actually changed.