Android Authority 's TL;DR (conveniently) doesn’t mention the actual downside to this update. But it’s fine imo, since this was actually a pretty insightful read.

My TL;DR:

• Google’s ARR/VRR implementation is hopefully more compatible with the GKI system vs. current per-vendor, per-device implementations
• To add this support, vendors must implement v3 of the Hardware Composer and Hardware Abstraction Layer APIs.
• That means also undoing existing kernel changes for their devices and retooling it to support HWC & HAL v3. Lots of engineering time.
• This solution still isnt perfect. There’s a notable limitation in something called the “panel’s Tearing Effect”, but im not an expert at displays so CTRL+F it for the paragraph in question.

Everything except the Mac line has a locked boot process. So your iPhone or iPad must run the latest iOS, must have an Apple ID, must source apps from Apple, and Apple has gotten so good at securing their devices that its basically killed hobbyist jailbreaking.

Anything you do on these multi thousand dollar devices is only because Apple allows you to— reluctantly, I might add.