No ADs available to get reward since ver 12.1.1

Only reward ADs are unavailable. ADs after game are normal.

I try these methods and still no working:

(1)  switch between mobile data and WLAN

(2) reinstall game

(3) clear cache

(4) use VPN and switch different nodes (US、JP、FR、DE、SG etc)

Location: China

Many Chinese players also have the same problem, both iOS and Android device.