510.47.03 DisplayPort link speed too low (4K @ 120 impossible, DP->HDMI 2.1, old bug reintroduced)

The old bug is back. This was fixed last spring, and the 470-495 series has worked fine. However when updating to 510, the DisplayPort link reported by Nvidia X Server settings is 4 lanes @ 5.4Gbps instead of the earlier 4 lanes @ 8.1Gbps and resolution maxes out at 4k@60Hz.

Hopefully this will be resolved.

Card is a 2080Ti with the Club3D DisplayPort to HDMI 2.1 adapter.