What does a normal formula fed, solids eating infant poop suppose to look like?

I am curently weaning, doing half bm and half formula for the past several days. N is 8.5 months and has been eating solids for 3 months with no allergies. I've refrained from adding new things in his diet since starting formula, but I've noticed his poop changing. It used to be logs, like adults, he never seemed to be straining when he went. Now it is mushy, like peanut butter? Was he constipated before (my supply had been dwindling) or having diarrhea now?