As it turned out, the issue of collaboration stood out sharply not only in our community but in Notion com too. The problems are not because members don't have anything to say, but because they don't feel like talking.
The need to talk arises only when a question shows up. From this point different motivations are born: gratitude, acceptance, development. The key task is to turn them on, in my opinion the easiest way is a sandbox for such collaborative knowledge creation.
The goal of such task is quite prosaic, encourage member to share and develop. Seed, water and grow personal and communal knowledge.