AMD writes MB, and they list the faster caches' sizes in KByte, where indeed I think it should be Mi and Ki respectively. And in the NV space (hdds, ssds) a GB means 10^9.
Reminds me of DDR vendors telling us that memory runs at 8GHz (8GT/s, 4GHz in reality).
If we are being padantic 1 MB is 10^6 bytes. 1 MiB would be 2^20
I thought of that soon after my comment but I felt my point was made even better because of the bad maths