When they do stuff like abducting gullible teenagers who tried to join the Wa army and send back chopped off fingers to their families i order to extort money, I think such measures are more than justified.
The Chinese government forced the Wa army to abandon drug trades in the 90s. However, it didn't take long for the Wa army to venture into casino and kidnapping. Now, telecom frauds become a big business for Wa army. It isn't like the Chinese government has not been patient with them or giving them ample of time to fix the issues. But too much money is involved and Wa army got greedy.
I think it is extremely good timing for the Chinese government to rein Wa army in at this moment. Burmese government is significantly weakened due to the civil unrest and the pandemics. So it probably won't have the resources and manpower to wage any offensive wars against Wa army. At the same time, Wa army is also devastated by the pandemics and seek the Chinese government's assistance. So there is no better time to do it and force Wa army to put an end to telecom fraud and casino and kidnapping.