Yellow poop in toddlers and children can sometimes be normal and is usually not caused by any disease or medical condition.
Most times the yellow poop that toddlers or children get is due to foods they've eaten and sometimes the yellow poop may be caused by things such as the gastrointestinal (GI) passage time which is very rapid especially when toddlers or children have diarrhea.
The toddler may also have a partial bowel blockage that may need treatment and if the yellow stool turns back to normal color after a few days then it's usually not a cause for concern.
However if the yellow stool or yellow poop continues after a few days or lasts longer than a week or doesn't go away then I would take the toddler to the doctor or go to urgent care and get the toddler checked out and tested for any potential problems.