Why didn't the PLA go to Myanmar to clean up the remnants of the Kuomintang?

China sent troops into Myanmar twice to destroy the remnants of the Kuomintang. However, because the remnants of the Kuomintang have been rooted in the local area for many years, they are very familiar with the terrain and are good at hiding. Basically, as soon as China's army entered Myanmar, the remnants ran away, and as soon as China withdrew, the remnants came back. So in the end, China didn't participate in the extinction. Until about 1980, the remnants of the army were merged into Thailand, and all of them became Thai nationals and became Thais.