The core of the law, ie who is expected to register their car in CA and what state sales taxes need to be paid has already been in place for years and likely already challenged. This is just a modifier to address a particular loophole.

As long as nothing about this crosses state lines (ie they’re not trying to regulate out of state businesses or property) there’s not a lot to go on. Several states have taken similar steps to close this loophole. Famously the YouTuber whistlindiesel got arrested in Tennessee for this and the case is still pending

https://www.thedrive.com/news/is-the-government-making-an-ex...