pre4 removed 3 data types including FixedQueue<> ([#1398](https://github.com/Unity-Technologies/com.unity.netcode.gameobjects/pull/1398)) which LagCompensation/TrackedObject.cs was using https://github.com/Unity-Technologies/multiplayer-community-contributions/blob/a37a913b4c3ae3021ff86ab9b2402bacfcf1a0fb/com.community.netcode.extensions/Runtime/LagCompensation/TrackedObject.cs#L18 not sure if you want to bring FixedQueue back or rewrite TrackedObject.cs? That's why I'm posting two issues, both here and https://github.com/Unity-Technologies/multiplayer-community-contributions/issues/140