It is indeed terrible. They copied the road color scheme of Apple Maps. It was a purely a marketing decision to make it easier for Apple customers to try Google Maps. Aside from being a dirty shameless ripoff imitation, it also made the map nearly impossible to use visually. Disaster.

Did it change just recently for you? On my phone it changed in November 2023 (12 months ago).

I ditched Google Maps for bike touring and now use Mapy.cz.