In a nutshell: Despite toting the same M1 chips as the new MacBooks and iMacs, the latest iPad Pros have so far been limited by a hard cap on how much RAM an app can use. The latest iPadOS beta looks set to change that, although it's unlikely to benefit most users.
The 2021 refresh of the iPad Pro -- dubbed "the fastest device of its kind" -- is available with either 8 GB or 16 GB of RAM, depending on the storage configuration selected. However, in May it was found that apps could only allocate themselves 5 GB of that capacity before crashing, even though the OS was still able to use the entirety of the device's memory.
Apple's second iOS and iPadOS 15 betas, passed on to developers on Thursday, allowed developers to request an entitlement that gives their apps access to more RAM, with its description in developer documentation outlining that it is only for "supported devices," and that the app must still behave correctly if it can't access more memory.
It also gives a function that can be called to determine the amount of RAM available, suggesting that there's not an explicitly defined higher ceiling for memory app usage.
Of course, the list of "supported devices" is likely limited to the most recent iPad Pros, as they're the only eligible with enough RAM to make the 5 GB limit a concern. Previous generations of the iPad Pro maxed out at 6 GB, and other models sit at 4 GB or below, hence the rule about behaving properly with less memory.
We've also yet to see apps that actually need more RAM than that, as the original 5 GB limit was only revealed by the developer of image editing app Artstudio Pro when stress testing the tablets.
Removing this limitation could be seen as positive news for iPad Pro owners, as it brings their tablets closer to parity with macOS laptops as Apple moves to unify its ecosystem with the M1 chip and beyond. We'll have to wait until fall to see it in App Store apps, however, as that's when iOS, iPadOS, and all the other updates announced at WWDC21 should arrive.