It's a bug and it only affects you if you use Liangshan troops.

I think its to do with the troops you are using and what you are fighting. I noticed only my Liao troops would rebel if I was at war with Liao, even if I maintained a high moral with them. It also seems to be based on the order you sort your troops. I placed my Liao wolf knights at the top (below me and my companions) and it was only those units that rebelled.

引用自 Moose On Goose：

I think its to do with the troops you are using and what you are fighting. I noticed only my Liao troops would rebel if I was at war with Liao, even if I maintained a high moral with them. It also seems to be based on the order you sort your troops. I placed my Liao wolf knights at the top (below me and my companions) and it was only those units that rebelled.

Correct, it's specific to who you are fighting against your own troops sort of rebel against you and join the enemy side. It's supposed to happen, so you have to be careful who you choose to bring with you when you're at war with people, or who you decide to attack, like Deserters using your type of troops. It's a very cool, but sometimes annoying aspect of the game, lol.