"She applied that principle to the cast, outfitting most of the characters somberly, their costumes rendered chiefly in tones of black, gray and sludge"

A look at the costumes in Russian Doll:

All tones of blue and green were struck from the production, Ms. Rogien said. “Blue in particular connotes a calm and tranquillity that is not present in ‘Russian Doll.’”

And from a look at the fashion in Umbrella Academy:

Poor Tom Hopper, he’d worked on this body and then we had to put a muscle suit over it. He was happy when we did flashbacks because you got to see him in a leaner kind of silhouette.

...

Getting the body suit constructed is the first step for anything of that nature. It really was quite a mass of muscle that we applied to him. One of the main challenges with that, and a big concern for him, was not to look like he had a tiny head with this massive body. So breaking up the body by opening up the jacket or having the neck exposed under the sternum, not just having a mass of one garment, kind of helps break him up so he wasn’t just this huge hulking being.