I've had a few events so far where the discussion/feedback part had 1-2 white guys doing longgggg monologues about something unrelated to the main topic. Last time had some stoner guy ranting about the confusing service at airports here (the event was about Gaza). Before that it was some boomer guy trying to explain Madonna to the non-white teens in our group (the event was about trans rights). Sometimes it's just two white guys monologuing back and forth. It's super counter productive and cringe.
I'm just thinking of a hard rule. Like "if you're a white guy, you're welcome, but please try to listen more and keep unrelated monologues to a minimum."
For the record, I am a white dude.
This isn't just white guy specific, though it will be more common. Some people just suck up all the air in a room. Having an effective moderator who can step in and politely cut people off/redirect the conversation on topic is a good idea. The following tips will be useful in moderating any kind of discussion, though I'll admit it's mainly geared towards groups of 15ish maximum.
(Fuck me, I was looking for a page discussing moderating small group discussions, but thanks to the enshittification of Google and SEO, all I can find is stupid advice for moderating focus groups from consultants. Thanks Google.)
Anyway, it's helpful to set norms and expectations early. I use the following system as an academic. I have people raise their hand to be put on a "primary" queue. This means they have a unique point or issue to raise. People raise a finger if they have an "immediate response" that's on topic regarding something the previous "primary" respondent said. You can just work your way down the queues, then, but you can set expectations about now long comments should be at the beginning. You can say "please keep your comments no longer than xyz minutes," and if people begin to go over you can politely remind them they've approached time. If they keep going instead of wrapping it up say something like, "in the interest of fairness and robust discussion I've gotta cut you off here to give comrades a chance to respond without also requiring too much time to address everything. Please keep the time limit and respect for your comrades in mind when answering."
If the discussion is moderated, you can then tweak the queue as needed to allow greater participation. If someone raises their hand a lot and no one else does, very well, but if you see that someone who hasn't spoken yet raises their hand you can easily say, "in order to hear from as many voices as possible we're going to go to ___________ next, and then we'll return to the usual queue." As long as you don't overuse or exploit this people generally appreciate and are amenable to the exception.
Yeah a lot of the other replies are good ideas, but having what we called a "strong chair" is the only systemic way to handle this. And you need to establish this as a norm over time, so the chair has support from the floor if needed.