#singleton

A [Sync(SyncFlags.FromHost)] field on a runtime-created singleton never replicates: the object needs NetworkSpawn, not just NetworkMode.Snapshot.

A static Instance claimed behind if (!IsProxy) in OnStart grabs the host's character on a joining client: the client camera follows the wrong player forever.

A singleton claimed in OnEnabled and nulled in OnDisabled traps any re-adopt poll that gates on Instance.IsValid(): the entity is never re-driven after a disable.

On the host, spawning a joiner's character clobbers the host's own camera-target singleton because IsProxy is false at Components.Create time: re-resolve the claim at the first OnFixedUpdate.