I'm looking to purchase a PCIE 4.0 riser too, but noticed that the link provided isn't fully 4.0 certified. I noticed the store also sells this newer model:
https://www.aliexpress.com/item/1005003814256898.html?spm=a2g0o.store_pc_groupList.8148356.5.142768feWePSZP
Would the 20cm R33SL 4.0...