The minimum versions of iPad Pro (M4) actually have 12 GB of RAM, not 8 GB
This applies to models with 256 GB and 512 GB of internal storage, for which Apple announced 8 GB of RAM. After the tablets went on sale, many bloggers, experts, and enthusiasts began to dissect them, revealing the memory chips.
It was found that in the model with 256 GB and 512 GB, two Z8DMS memory chips are installed, which corresponds to plates of 6 GB each: altogether this amounts to 12 GB.
Most likely, Apple used 6 GB chips to optimize costs. Possibly, suppliers such as Micron, Hynix and Samsung did not offer 4 GB chips as a standard solution for LPDDR5 or LPDDR5X memory, and custom designing them for the iPad would have been unjustifiably expensive, so Apple simply used 6 GB chips and purposely limited their capacity to create a larger differentiation within the iPad Pro lineup.
As a result, about 30% of the available memory is not used. However, we can at least expect that the new MacBook Air and base Pro models with M4 will come with a minimum of 12 GB of RAM instead of 8 GB.
Interestingly, the iPad Pro (M4) models with 1 TB and 2 TB have two 8 GB RAM modules, matching the 16 GB RAM specification stated by Apple.