I can confirm this, I have the same problem with gmktec X2 device, the system reserves the memory on forehand. 32gb is not enough for games these days, I put it also on 16gb vram, which leaves me with 16gb for hungry windows 11 with ai stuff...
It's not just an AMD thing,lunar lake from intel also States that 50% could be used by the igpu.
That's because these new igpus and npus need ram, lots of ram. Because they are not the same poor igpus as we knew before. They finally start to compete with discrete cards. At the cost of ram because they don't have dedicated vram ..
I've now ordered the 128gb version because 64 might also be on the narrow side for local ai apps