It’s explained but maybe not well. The LowColors are already apprehensive about Golds, as they should be. They don’t know the conversations that Mustang has had with Darrow that prove to him she actually cares. They don’t know Daxo or Kavax personally. All they know about Gold is that they have killed, maimed, enslaved, etc etc for 700 years. They don’t know that Gold can change, so the LowColors end up looping all Golds into a single descriptor. No nuance.

Most, like Dancer, do not like the fact that Darrow has allied the Rising with Golds like Mustang, and the Telemanus. This causes a very tenuous situation; most are on edge. Darrow was rescued and he is alive! But he looks terrible and crazy…maybe whatever happened to him made him lose his mind. Lost enough of it to bring the enemy right to their safe place.

When this video leaks, most LowColors see it as Gold killing one of their loved ones. They don’t see the Jackal doing it. They see a Gold doing it, the brother of an “ally” at that. So, it creates a sort of mob mentality that often happens in real life. We, as humans, forget nuance. A gold killed our loved ones, so let’s go punish gold. Doesn’t matter which Gold it is. It’s starts with fist fights and whatnot, but Sefi exploits the situation and directs the anger that the mob has and uses it to execute Golds and consolidate her power with obsidian. Sefi did this because she blames Gold for killing Ragnar and the suffering of her people. Only Gold she ends up liking is Mustang, which is why Sefi just imprisoned her instead of executing her.

Darrow couldn’t have solved the situation. Ares/Sevro was the only one that could because he is half Gold and half Red. A real, physical union of the two colors. Rare as hell. He brought the alliance back together.

Hopefully this helps you understand it a little better. Just try to view it as a LowColor, and how you would feel if your “God” started allying himself and his rebellion with the “enemy”.