Persistent Plugin Issues: "No plugin manifest found" with LavaSrc & "Please sign in" with youtube-plugin

[FDJHBYB]

Hello everyone,

I'm setting up a Lavalink server for my Discord bot and have run into a persistent and complex issue that I haven't been able to solve after extensive troubleshooting. I would greatly appreciate any expert insight.

My Environment:

Lavalink Version: 4.1.1
Java Version: 17
OS: Windows Server
The Problem:

I am facing two different issues depending on the YouTube plugin I use:

1. With lavasrc-4.7.0.jar (The Recommended Plugin):

This is the plugin I want to use. However, Lavalink fails to start every single time.

Steps Taken: I create a completely clean directory containing only Lavalink.jar and an application.yml file. I then create a plugins folder and place a freshly downloaded lavasrc-4.7.0.jar inside.
Result: Lavalink crashes on startup.
Error: The root cause is always java.lang.RuntimeException: No plugin manifest found in .\plugins\lavasrc-4.7.0.jar. This error persists even after trying multiple clean directories and re-downloading the JAR file multiple times to ensure it's not corrupted.
2. With youtube-plugin-1.13.3.jar (The Older Plugin):

Following advice to test this, I tried the older plugin.

Partial Success: Surprisingly, with this JAR in the plugins folder, Lavalink starts successfully! It doesn't crash with the "manifest" error. My bot can connect, and it can successfully search for tracks using ytsearch.
The Failure: The problem occurs during playback. When Lavalink tries to play a track, it fails immediately.
Error: The log shows a com.sedmelluq.discord.lavaplayer.tools.FriendlyException: Please sign in.
Attempted Fix: To solve this, I created a new burner Google account, enabled 2FA, and generated a 16-digit App Password. I configured my application.yml with the email and the App Password, but the Please sign in error still occurs.
Summary of My Dilemma:

I am stuck in a difficult situation:

The recommended modern plugin (LavaSrc) fails to load entirely on my system for an unknown environmental reason.
The old plugin (youtube-plugin) loads successfully but fails during playback due to the Please sign in error, and its email/password authentication method doesn't seem to work.
My Questions for the Community:

What could be causing the persistent No plugin manifest found error with LavaSrc on a Windows Server environment, even when the setup is perfectly clean? Are there known issues with file permissions or antivirus software?
Is the email/password authentication method for the old youtube-plugin now deprecated by Google, making the Please sign in error unfixable with that plugin?
I am available for a screenshare session if an expert has time to look at my setup directly, as I suspect the root cause is an environmental issue.

Thank you for your time and any help you can provide.

[devoxin]

and generated a 16-digit App Password. I configured my application.yml

This is not how you enable oauth in youtube-source. I recommend reading the README again as it details how to properly link an account for oauth usage.