Couldn’t be anyone other than Ruth Wolf-Rehfeldt. You get a feeling for texture, dimensionality and depth only though prolonged play with different characters on the typewriter keyboard. I know that ‘m’ well. It’s probably the most blocky and therefore the darkest shade you can achieve on the Lettera 22 with a single layer character (also the ‘M’).

This from an edition ‘Typewritings - Concrete Figure’ you can view more here ↓

https://sbirky.moravska-galerie.cz/dilo/CZE:MG.JV_6760/zoom