Ultra = a communist who rejects materialism and maintains liberal idealism when understanding socialism and communism.
They fetishize defeat which is why the perfect communist revolutions are those that failed and the perfect revolutionaries are those who refused to compromise liberal moralism, while communists who lifted hundreds of millions out of poverty and rolled back empires have dirty hands because they didn’t tie them behind their backs.
Many ultras are trots, yes. I think of trots as those well educated elitist fauxcialists who believe the revolution belongs to the intellectuals rather than the people.
But you get many flavors of ultras. The common denominator is that whatever works isn’t pure enough and so must be fought even harder than the oppressor.
“The revolution in X was betrayed, even though they made things a lot better the moral stain of actually existing makes them worse than the empire.”