We've covered giving a coworker feedback on Slack. This is the harder version: the feedback goes up. Your manager talks over you in demos, or changed the deadline without telling the team, or their "quick thoughts" on your work arrive as public teardowns. Something needs saying, and the person who needs to hear it writes your performance review.
The standard advice is don't, at least not in writing, and the caution isn't paranoid. Power changes how words read. The same sentence that's "direct" between peers can read as insubordinate going up, and text strips the tone that would have softened it. But the don't-ever camp quietly assumes silence is free, and it isn't. A manager who never hears the truth from below doesn't become a better manager, and you don't become less resentful. Most managers, and this is the underreported fact, are starving for upward feedback. They get performance reviews from above and silence from below, and the person who tells them something true and useful, well, becomes one of the most valuable people on their team. The move isn't avoidance. It's craft.
Craft rule one: private, always. Public upward feedback isn't feedback, it's a challenge, and even a secure manager has to respond to the audience instead of the point. DM, or better, ask for ten minutes and use Slack just to open the door: "Something small I'd like to share from the last few sprint reviews, got ten minutes this week?" Serious feedback often deserves voice, but the written version works when it's built right.
Rule two: frame it as information about effect, not judgment about them. Your standing to give upward feedback comes from the one thing you can see that they can't: what their behavior does at your altitude. Stay on that ground and you're unassailable, because you're the world expert on it. "When the deadline moved without a heads up, three of us kept building against the old date and lost two days" is testimony. "You need to communicate better" is a review, and reviews go downward. The formula, roughly: the specific event, the effect you observed, and, optionally, what would help. Then stop. No essay, no pattern-of-behavior prosecution, one event at a time.
Rule three: give them an exit ramp. Upward feedback that corners a manager gets defended against; feedback with room in it gets absorbed. One clause does it: "totally possible there's context I'm missing." That's not groveling, it's true, there usually is context, and it converts the message from verdict to question, which is the register a manager can actually respond to without armor.
Assembled:
Hey, small thing from Thursday's demo, sharing because I'd want to know if it were me. When my section got summarized before I presented it, I lost the thread of what was left to say, and I've noticed I'm not the only one it happens to. Totally possible there's a reason from your side. But if it's just momentum, a beat for each person to finish would make those demos work better for us.
Specific, effect based, exit ramp included, and quietly brave. Send that and one of two things happens: you learn your manager can hear things, which is worth knowing, or you learn they can't, which is worth knowing more. Either way you've stopped paying the silent tax, and you've paid market rate instead: one carefully built message.