Backplane MGT vs LVDS lanes routing
Why all the meanders on LVDS lanes going to the backplane? These are low speed lines and they are not length matched neither on the backplane nor on the system board.
On the other hand the routing of MGT diff pairs (BP_MGT.Rx/Tx) from the backplane could be improved as these are high-speed lines. Route them in L12 (today they are in L10) to avoid stubs on vias when transitioning to L1 and use curved corners.