Simply put, the hordes during boss fights really have to stop. It’s awful to get right near the end of a level, close to the finale and get a horde + boss. There’s very little you can do in a lot of places, especially when you add the fact specials such as hookrats are spawning. On higher difficulties it just seems like the game has outright decided you lose when those happen all at once.
I’m fine with a horde spawning instantly after a boss fight or right before one but in the middle… i just lose every time. The only way i’ve ever dealt with it is with someone distracting the boss and being lucky enough for the horde not to attack when it’s aiming at that 1 person. If the horde ever decides to attack you while a boss is on you, there is no chance of survival.