This isn't a new thing in the Tour and it is normally not a problem, but since someone crashed on it then it must be the "white shit" that caused it. Not one of the hundreds of other variables - like the rider.
Several riders independently crashed in the exact same spot, including Pidcock who is a famously good descender.
These are literally world class professionals at riding their bikes downhill around corners without crashing. If they say the white shit caused the roads to behave differently than they expected, I'm going to believe them.
Paint is usually slippery. There are special standards for how slippery a paint painted on the tarmac can be. But it’s calculated for cars, not racing bicycles with teeny-weeny tires. Could have been easily the paint.
I mean, one of the first things they teach in motorcycle safety classes is that the road stripes are slippery and could cause a crash, especially in the rain. Even if there us a standard for how slippery it can be, it still doesn't match the traction of the road surface.
These are literally world class professionals at riding their bikes downhill around corners without crashing. If they say the white shit caused the roads to behave differently than they expected, I'm going to believe them.