The 20.12 kg figure is a handling and mounting number, not a selection one
The drive is listed at 20.12 kgs, which is enough mass that two technicians are the right call for unbolting it from a crate or lifting it onto a DIN-backplate, and a panel builder needs to confirm the backplate and cabinet bracing are sized for that static load before the drive is bolted in. For comparison the ACS880-01-040A-5 comes in at 18.14 kgs and the ACS880-01-065A-5 at 23.13 kgs, with the ACS550-U1-096A-4 at 19.96 kgs, so this ACS800 configured build lands in the same physical envelope as the modern ACS880 generation and the older ACS550 line — the delta is not a footprint-class change.