For the average user, updating to 3.10 is mandatory. If you remain on version 3.09, you cannot play online due to server-side version enforcement.
How to obtain Warzone Mobile legally and safely (actionable) warzone mobile 3.10 ipa
As of the current season (Season 3/4 timeline), Activision has been aggressively updating Warzone Mobile to bridge the gap with its console counterpart. Users searching for version 3.10 are likely looking for the specific build that introduced: For the average user, updating to 3