Volutella Boxwood Blight
Here is our page on boxwood volutella which explains management options: https://extension.umd.edu/hgic/topics/volutella-blight-boxwood
As you'll read, spraying is done early in the growing season and sometimes later. Timing is important. Only one fungicide is used per spraying.
Infected branches cannot be cured and should be pruned out (like the yellowing one in the last photo.)