I don’t think that his dad keeping him that one day is the issue. My child used to do regularly. It was helpful for me that his teacher would check in with me once I left and seemed to always confirm that like a light switch, he would go into happy mode. With mine, it just seemed like separation anxiety… esp going from hanging out with me where he received 100% of my attention to having to share space with other children.
Something is happening at daycare.