Almost 3 year old suddenly waking at night

Our Son turns 3 in January. He was always a good sleeper as we was on the Nanit program since 2 months of age.

He doesn’t currently nap during the day we had to drop this earlier this year because he was having a lot of night wakings. He has a new sibling that arrived 2 months ago and still managed to sleep through the night. He has been in a toddler bed for over a year now.