AMD pivots from HBM to LPDDR5X for new Versal Gen 2 memory on package chips (servethehome.com)

Where did you get these numbers, or rather think they would apply as they are?

The artice speaks of 288GB/s for LPDDR5x as it will be stacked.

Still slower than HBM, but not by as much as you make it.

From page two: (https://www.servethehome.com/amd-pivots-from-hbm-to-lpddr5x-...)

    With AMD’s Versal HBM products, the company was able to offer up to 32GB of memory with 819GB/second of memory bandwidth; meanwhile the new Versal Gen 2 Memory on Package chips will offer 32GB of LPDDR5X with just 288GB/second of memory bandwidth.

It's an almost 65% drop in bandwidth, which is still significant, but no 90%+ significant.