Thailand is on a list maintained by the Chinese government - it's not a good list.
There's some very weird stuff happening over the last few months :
It's not clear if this is nationwide or just in a handful of places......
"Local police stations are carrying out strict review processes for people leaving China, particularly if they're going to Thailand, Cambodia or other Southeast Asian countries,"
Read this : https://www.rfa.org/english/news/china/travel-restrictions-02202023160935.html