They are dragging their feet (the bracket manufacturers) on moving to PCIE 4.0 cables. I've been after coolermaster about it too, but they would not commit to a ETA for the option.
When I bought my bracket I had to return the cable as I could not get it to fit without bending the crap out of it. So for now, I'm on PCIE 3.0 and if I want to upgrade my BIOS need to remove the bracket assembly completely. Not exactly convenient.