If there is an imagery in the MCU that serves as both shock value and a sign of a character's mental derangement, the scene of Captain America's shield being stained with blood probably takes the top slot.
It's truly unsettling to see one of the MCU's symbols being defiled in a manner such as this. Not to say people haven't died to it before, but most of the time they were Nazis or genocidal aliens, not a group of misguided radicals just trying to fix the world in their own way.
But that's what the series is about. Gritty, in-your-face drama with some rather uncomfortable questions asked via its characters: What if Captain America was a bully? What if 'hope' was just a matter of perspective for someone, rather than a real possibility? Some of them remain to be answered, while others, not so much.
Taking off from the explosive end of episode 3, The Falcon and the Winter Soldier finally delves into a bit of Bucky's history with his Winter Soldier deprogramming at Wakanda with the Dora Milaje, as Bucky strikes a deal with one of them to let him have Zemo for eight hours, while the trio tries to hunt down Karli in hopes of dissuading her from terrorism.
Meanwhile, Captain America, now almost over the edge with frustration, really starts to crack as he tracks the trio down and forces their cooperation with the intent of stopping Karli by any means. John Walker is an unhinged man here, and Wyatt Russell deserves high praise for successfully portraying someone who should be an ideal soldier and a good man, but really is a flawed human being with too much power and baggage on his shoulders.
The episode also shows Karli's desperation for getting things her way as she brazenly threatens Sam's family, leading to an unnecessary confrontation where there was once a chance of peaceful reconciliation. The positively angry Power Broker remains a mystery yet, but at least for now, the super-soldier serums are mostly destroyed.
Interestingly, it appears that no matter which way the series turns out, it's Zemo who is standing to profit from the chaos anyway. At this point, it is clear that he's not the Power Broker, but it is undeniable that his abilities of persuasion are second to none - even without a disguise or a mask. It remains to be seen what will become of the character and what repercussions he will have on the post-Avengers world.