Inconsistency in order of Start() and OnStartAuthority() calls on the Spawnable Objects between Host and Client:
- on the Host - first is Start() called
- on the Client - first is OnStartAuthority()

How we can reproduce it using the example you attached
--- please see attached video in comments ---
1 Open attached project and open scene "sc1"
2 Press Play -> LAN Host and press "Space"-button on the keyboard - notice that Start() is called first (logs in the Console)
3 Exit Play mode
4 Build and Run Standalone player and start "Server Only"
5 In Editor press Play and start "Client" -> then press "Space"-button on the keyboard - notice that OnStartAuthority() is called first (logs in the Console)

Actual result:
as you can see in the Console - the order of calling Start() and OnStartAuthority() is different

Expected result:
order of calling Start() and OnStartAuthority() should be the same on the Host and on the Client