I was playing Gymnasia, and changed from tribal for a monarchy with the missions tree.
Next thing I know, a dude with fucking 90 support appear, rebel, and game over. Couldn't even raise my troops, he had all the provinces but the capital.
Why did that happen?
Civil wars are broken, it's an old issue. Not only can the disloyalty threshold calculations be wrong, but the rebellions can spawn with 3000 gold, which they just get basically by magic.