On a map, all blocks get summarised by their primary color, which i believe has a field on the Block object. All shingles slabs and stairs use the color of undyed terracotta. (not tested the shingles block or vertical slab)

attached is a screenshot of a map made with quark 1.16.3, and a screenshot showing the actual roofcolors, cyan terracotta shingles and green terracotta shingles.

I can do the legwork to find out if other versions are affected, if desired.

Can't reproduce. Make sure you're using the latest version.