It's mainly info gleaned from the overall drop in performance of AP1 after the divorce, and the time it took Tesla to achieve parity with the previous Mobileye-only solution. So lots of reading between the lines, mostly because the whole program is a closely held secret.
This
Sep 15, 2016 article from the LA Times is pretty revealing, though:
"Tesla Motors and parts supplier Mobileye broke up in July. Now the two sides are dissing each other with wildly different takes on what caused the split.
But Tesla says that wasn’t the reason for the companies’ split. A spokeswoman for the automaker told The Times on Thursday afternoon that the reason Mobileye was mad is because Tesla was developing a video-processing system of its own. When Mobileye found out, it “attempted to force Tesla to discontinue this development, pay them more, and use their products in future hardware,” the spokeswoman said.
When Tesla refused, she said, Mobileye “discontinued hardware support for future platforms and released public statements implying that this discontinuance was motivated by safety concerns.” At the time, Mobileye said it would end its relationship with Tesla when its current contract ran out."
So my inpression is that when Mobileye discontinued support for AP1, that meant they would nolonger provide software/firmware updates for AP1. This was part of their business strategy to put maximum pressure on Tesla, hoping that they would cave on Mobileye's demands that Tesla stop their own in-house software vision development program.
Well, at least it seems that Panasonic was paying attention back in July 2016 when an outside supplier tried to force Elon's hand. Mobileye will lose badly on this gambit over the coming years. Elon might not even have pushed so hard for FSD if not for them. And now that Tesla is a chipmaker/designer with an exciting product roadmap, Mobileye doesn't seem to have any advantages at all. Certainly Tesla isn't giving them any data from AP1 cars to train a NN.
Game. Set. Match.
Cheers!