I don't think that's the case:

"The Thai Government, in a late-night order released around 10:00 P.M. on June 23rd, 2022, has dropped a divisive mask mandate in all public areas.The mandate previously required one to wear masks in all public places, even outdoors or alone."

https://thepattayanews.com/2022/06/2...gazette-order/

I've been in a couple of offices here in Chiang Mai where the staff is wearing a mask but once I remove mine, the staff does the same. The overwhelming number of Thais that I see though are still masking up, even outdoors and even when alone outdoors.