Strange renders on the Mapnik map

Have anyone else seen some roads recently turned grey, like this on the map in Stockholm, very strance stuff.

This is only apearing on specific tiles , so I’m guessing it’s part of the postprocess that is done on these.

I think the problem occurs because the images are palletized and sometimes an important colour doesn’t make it onto the pallet.

This tile has had a similar problem for a long time so I’m not sure it’s a recent problem.

Perhaps the data on your tile has recently changed triggering the problem.

That sounds like the problem yes… It really is a cumbersome problem to solve.