Thank you everyone for your advice! I will be bringing this information to my husband and we will come up with a game plan.

So we have a 3-year-old son nonverbal ASD. He does the same thing all the time. It is quite frustrating. One of the therapists said it is sensory related. We're still working on the potty training ourselves. But we bought onesies off Amazon that we put him in throughout the day because he was also smearing. It on the walls squeezing it between his hands, sometimes getting it on his face and clothes. So like I said we put him in onesies throughout the day

Structured Routines:
Consistent Toilet Routine: Establish regular bathroom breaks and routines to promote predictable and appropriate toileting habits.
Social Stories: Utilize visual narratives to help individuals understand and learn appropriate bathroom behaviors

It can be linked to sensory sensitivities, communication difficulties, or medical issues common in autistic individuals.
Behavioral Interventions:
Positive reinforcement for appropriate behaviors and consistent expectations can help reduce the likelihood of smearing.
Creating a Positive Toilet Experience:
Ensuring the toilet is comfortable and accessible can reduce anxiety and aversion to using the toilet.
Maintaining Emotional Neutrality:
Caregivers should remain calm and neutral when the behavior occurs to avoid inadvertently reinforcing it.