Cohort view: fixes the create date to the selected week, then shows how many of those leads are — as of right now — members of your MQLs / SQLs / Clients segments. Populations come from your own HubSpot segments (lists 2186–2192), independent of the Weekly Snapshot tab's deal-based definition, so the two views can disagree by design. Very recent weeks will show low downstream numbers simply because not enough time has passed for leads to move through the funnel yet.