Against what is mentioned in other comments I suggest that all the information and discussion should happen in your documentation platform. Confluence, notion, even Jira.
While slack seems like popular suggestion, its not made to keep structured information and what happens is that you have some discussion in slack, some discussion in a meeting that was not recorded and then, in a best case scenario, some conclusion in Confluence. This is a bummer because a lot of information was lost, specially the logic behind a decision. It would be far better if the discussion happened in writing within the comments section of the document. Now all the context is in a single place and searchable. Plus its possible to add to it somewhere in the future, so the document base doesn't necessarily grow with time.