I think 2 great community activity indicators are - Github issues and of slack/discord/discourse comments. One key thing with github issues in my opinions is that, If the github issues are mostly by the core team, it is not a great sign. You want a large mix of issues from customers or users and not from the team. This is a good indicator if the project is solving real problem or not. Stars is very low threshold action. Same goes with the slack comments, it should have both volume and freshness.
In a very strange way (but reflective of the economic regime) a startup that fakes stars vs a straight-arrow startup that doesn't is demonstrating a key element for success in business, which seems to require a significant element of bullshiting, and outright deceiving. The mantra has been that "grow grow grow" is the only guideline for success. Inflating your stars is just rookie hour practice for bigger better growth b.s. down the line.