I've been on the Rands Leadership Slack since the earliest days. There are some good parts, but you really have to work hard to separate the wheat from the chaff.
Most big channels are dominated by people who seem to have unlimited time to insert themselves into every single conversation. They give advice whether they're qualified to or not. There's a lot of uncomfortable tension among some of the regulars who are more interested in outcompeting other people's responses rather than having a group discussion.
Some of the community celebrities are only popular because they're active in the Slack all day long and will provide a semi-friendly response (with heavy use of emojis) to every discussion. It feels like a popularity contest, or at least that's how some people are treating it.
It's also the most rules-heavy Slack or Discord I've ever seen. Too many of the users think it's their duty to police everything in the Slack, including how other people are using it. If you start discussing something and the conversation involves an adjacent topic, be prepared for an influx of people demanding you move the conversation to another channel dedicated to that topic (of which there are thousands). Move the conversation to that channel and it will die, because few people are interested in joining hundreds of channels to micromanage every little topic.
There are occasionally gems to be found there, but it felt like grueling work every time I tried to participate or ask questions. Asking questions requires a huge amount of pre-defensiveness to fend off all of the people taking the worst possible interpretations. Contrary to the name, the audience is largely ICs, not managers, and they'll gladly explain to you that leadership and management are not the same. While true, conversations dominated by ICs tend to have a very IC-biased mindset, meaning any managerial questions you ask will be met with a "customer is always right" mindset where people think it's the manager's job to accommodate the IC employee, regardless of the issue.
I still check in occasionally, but it basically feels like LinkedIn in chat form unless you can stick to a few hidden channels with good signal to noise ratios.
I'm still looking for some sort of Staff Engineer type of community, but I'm afraid it will be impossible to handle publicly with open invitations. Too much attention from the people who have free time, not enough attention from the people busy doing the work.