Reproduction steps:
1. Open the “IN-10718_NetcodeEmbed“ project and open the “SampleScene” scene
2. Embed the “Library/PackageCache/com.unity.netcode@VERSION” package by dragging it into the “Packages” folder
3. Observe the Console
4. Remove the “@VERSION” part from the embedded package folder name
5. Select “BuildConfiguration/Server” in the Project Browser
6. Select your platform and click “Build and Run”
7. Open the PlayMode Tools window (Multiplayer > PlayMode Tools)
8. Set “PlayMode Type” to “Client” and “Client auto connect address” to “127.0.0.1”
9. Enter the Play mode

Expected result: No errors
Actual result: FileNotFoundException is logged after step 3 and “RpcSystem received bad protocol version“ is logged after step 9

Reproduced in: 0.51.0-preview.32, 0.51.1-preview.21 (2020.3.39f1, 2021.3.9f1)

Reproduced using: Windows 11, macOS Monterey 12.0.1

Notes:
1. Not reproduced when not embedding the package
2. Other packages do not error when embedded containing “@VERSION”