Come join us at the new site
https://forum.daycare.com
My guess is that they are trained and taking him to the potty at home and possibly even getting up in the night to have him go pee. I had a friend once tell me that that's how she night trained her girls. She would set an alarm go in wake them up take him to the bathroom and talk him back in.
In 2020 I had three kids potty training, they all potty trained differently. One potty trained during lockdown but then when he came back I would have to remind him that it was okay to go potty or he would wet himself because he wasn't use to using my bathroom.
One was typical as soon as he was ready he got it but Mom tried for a year before he was ready.
The third and the oldest had no interest in even attempting here. Then I went on vacation when I came back she was asking to use the bathroom the first couple days and then stopped. Then I had to quarantine for 2 weeks and when she came back she was fully potty trained. The key was having mom and dad exclusively.