Hi! After the mechanical edit that took place, I also started reviewing and adding tags to paths that have material=sandstone now.

As far as I understood, ways with surface=paving_stones should be tagged with paving_stones:surface=sandstone instead of surface=sandstone. See Wiki https://wiki.openstreetmap.org/wiki/Key:material ("For surface=paving_stones there is paving_stones:material=* tag")

Unfortunately, it is a special case (I also find it a bit strange to be honest + increases the effort). but perhaps the way https://www.openstreetmap.org/way/1070794775 should be changed ... Best regards!