Interesting screenshot I managed to capture, first time seeing this
although this may be the result of me trying to troubleshoot this problem. I deleted the "blueprint-storage.dat" in the "%appdata%/Factorio" folder but replaced it again before getting this screenshot
the idea I had was to somehow clear the cache of my blueprints so that I do not have the window pop up due to it remember the last time I was on the server I had it open. having hte window open means I am pre-rendered into the game at 6fps and inputs do not go through properly so it becomes impossible to get out of the blueprint window. additionally when pressing B to close the blueprint window, if you are lagging the game seems to duplicate this command and send press B down the nB up then B down again, so the window continually flashes open and closed. if the time it is closed is great enough your fps will increase and the commands will be receive properly again, only sending B down B up once and getting you out of this never ending loop of frustration.