How to reproduce:
1. Open the attached project "MPS_LegacyPackageConflict"
2. Observe the Console
Expected results: The migration path validator warns that the installed packages are incompatible with the Multiplayer Services SDK and names the packages to remove
Actual results: No warning is shown and 36 "CS0433" errors are thrown, e.g. "error CS0433: The type 'LobbyService' exists in both 'Unity.Services.Lobbies' and 'Unity.Services.Multiplayer'"
Reproducible with: com.unity.services.multiplayer 2.3.1 + com.unity.services.lobby 1.3.0 + com.unity.services.matchmaker 1.2.0 (6000.0.81f1, 6000.5.10f1)
Reproducible on: macOS Tahoe 26 (M1)
Not reproducible on: No other environment tested
Note: The Multiplayer Services SDK re-declares 75 public types under the same fully qualified names as the standalone Lobby and Matchmaker packages (all of Unity.Services.Lobbies., Unity.Services.Matchmaker. and the global-namespace type LobbyEventCallbacks), so any user code that references them stops compiling as soon as both are present.