Ah it doing that is it he become shit head or still nice head
Judging by the two previous pics, I'd take it as a nicehead doing something a normal pet yu would do. Being living creatures, yukkuri need to expell their defecations periodically. If it were that she's doing it out of the toilet or in a way to say "eat Reimu's Mr. poo poo", that'd clearly be from a shithead.