I want to say that it's most likely a over-eager "new tarmac" shader conflicting with a pp-filter? And the racing-line has the "groove" texture overlaid making it look different? I looks like if the groove wasn't there, the track would be that dark full-width? Perhaps test with the standard pure pp-filter?
Another thread to pull perhaps, is: My AC used to look like that when we all first moved to LCS. Really bright (white) at the horizon, weird blue above, nuclear grass, very strong contrast etc.
@Peter Boese dropped a gem while helping someone else, and led to me turning off all HDR related stuff in Windows and CSP. Worked a treat. That could be making the blackity-black maybe?