I've two different PC and when I lauch Illustrator with the same file, I see great differences on the memory usage. In one PC, it uses 114 MB while in the other PC, it uses 1.230 MB.
The PCs have the same software - W10Pro 64 bit - and the Adobe CC is the same.
Thanks for sharing the details and the screenshots! Could you please confirm the exact version of Illustrator 2021 you're using on both machines? While both PCs might be running the same OS and CC version, hardware differences like the available RAM, graphics card, or even processor type can impact how Illustrator allocates and uses memory.