https://wccftech.com/m1-ipad-pro-apps-limited-5gb-ram/

Apple certainly outdid itself, not only when it unveiled the M1 iPad Pro, but revealing that customers can configure it with up to 16GB RAM if they can pay for it. This makes the flagship tablet no less than sporting desktop-level hardware, but unfortunately, it is the iPadOS platform that severely limits the new slate. According to a forum post, apps are limited to using just 5GB of RAM, irrespective of how much memory your iPad Pro ships with.

To remind you, the M1 iPad Pro ships in 8GB RAM and 16GB RAM configurations. Customers will only gain access to 16GB RAM if they purchase the 1TB or 2TB storage variants, and that will require some extra cash on the part of the customer. Unfortunately, even if you purchase the 16GB RAM version thinking it will benefit you, we have to be the bearer of terrible news.