Why is it that all the UHD-friendly drives are LG models?
Firmware hacks. Earlier versions shared at least one common loophole that could be exploited. I believe what happened was that bus encryption (a security feature required by AACS 2.0) could be disabled, essentially causing the decryption process to be like AACS 1.0. I’m sure the exact answer is more nuanced than that but that’s my basic understanding of what happened. The loophole was closed eventually but people figured out how to downgrade the firmware on the drives back to versions with the loophole.
Blu-ray drives can read UHD discs because of certain defects. Instead of executing the AACS 2.0 rules, they execute the AACS 1.0 rules, which allows us to decrypt and read them according to the blu-ray method. We call this kind of optical drives “UHD friendly drives. If you have old blu-ray drive that having that defects.
Not recommended updating the firmware if you owned old drives, and this will remove your Blu-ray UHD friendly drive. Because the methods of updating the firmware are very complex, even if you can use some tool software to quickly complete the firmware update and then you decided to downgrade again, there is still the possibility for failure.
Honestly, while downgrading is always a risk, the process was greatly simplified recently. The original downgrade procedure was scary and had a lot of strange nuances. Eventually, somebody modded the official Asus/LG firmware upgrade tool to ignore the downgrade check. The modified tool cheerfully flashes older firmware without any issues. I’ve downgraded a couple of drives without any issues. I’d recommend it to anybody who doesn’t want to take risks with the older, much more manual method.