We just released a hotfix for Homeworld 3. This hotfix reduces friction caused by the “mod mismatch” error when joining multiplayer lobbies.
In an effort to avoid multiplayer match desyncs caused by mismatched mods between players, this pop-up was added. This hotfix changes the behavior of that mod mismatch verification to only affect modded skirmish maps selected in the lobby. Players will still see the error upon trying to join a lobby where the map selected is a modded map that they do not have installed. They will also see the error when the lobby host changes the map selection to a map that the client does not have installed.
Manually installed mods (in the pak folder) are no longer detected by this system and so multiplayer match desyncs might still happen due to mods creating an imbalance, but now you will be able to enter lobbies and discuss with other players if needed.