Does Blightreach buff replace blighted maps with lower tier ones?

Idk if red map blights still guarantee all blighted maps found in chests to be red-tier, but I often see useless white and yellow maps dropping instead. I suspect that Blightreach replaces them because this passive forces low-tier maps spawn despite all maps on atlas already being T16.

Am I right about this? If so, the worst part is that Blightreach is granted by the node which gives 60% more chance to loot blighted maps. Like, why? Why does this buff even exist? It ruins even normal T16 map drops, because any T16 map is always better than T1-T12 blighted one.