The article doesn't say it's now a grade 2 screen. The article does quote Mentor Graphics saying, "defining the boundary conditions for Innolux’s system is the responsibility of their customer, not Innolux."
So Innolux will quite happily sell Tesla a screen, but it's up to Tesla to use it appropriately. I think your understanding is wrong.
> Tesla appeared to mostly fix this problem with its "cabin overheat protection" feature ... as well as revisions to the Innolux panel.
For what it's worth, the TM3 appears to use an LG LA154WU1-SL01, but I can't find a detailed spec sheet on it.