Floodgate player name prefixes are not working with ProtocolLib

[Smart123s]

What behaviour is observed:

When I join the game, my name is Smart123s.
In the log: Smart123s left the game

If I delete FastLogin.jar from the plugins folder, the prefixes are added to the player's name as excepted.

What behaviour is expected:

When I join the game, my name should be *Smart123s.
In the log: *Smart123s left the game

Steps/models to reproduce:

Install the plugins mentioned below, and login from Bedrock Edition.

Plugin list:

AuthMe, FastLogin, Geyser-Spigot, floodgate-bukkit, ProtocolLib, Skinsrestorer

Environment description

Default DB for all plugins.
Java 14, Ubuntu 20.04, MC v1.16.5, Paper-553, No Bungeecord or Proxy
Connected to server using an Android device.
The issue is present both on LAN and on Cellular

Plugin version or build number (don't write latest):

Build #968

Server Log:

None

Configuration:

Note: other entries have not been modified

autoRegister: false
secondAttemptCracked: true
switchMode: false
premiumUuid: true
nameChangeCheck: false
forwardSkin: true
premium-warning: true
mojang-request-limit: 600
auto-register-unknown: false
autoLogin: true

Floodgate's config:

username-prefix: "*"

Geyser's config:

remote:
    auth-type: floodgate

[t0ssox]

This bug causes that a significant number of players (for my small server) cannot enter via bedrock because most have the same nickname on Bedrock and Java. Hope this will be fixed in the future.

[Smart123s]

I've done some debugging and now I am even more confused than I was before.

The problem seems to be in ProtocolLibListener.java.

Commenting out the contents of the register() function, or stopping the listener it from registering in any other way will make Floodgate prefixes appear. (And yes, it also breaks the plugin.)

However commenting out the contents of onPacketReceiving(), so effectively registering an empty event will cause the prefixes to be broken again.

Switching from ProtocolLib to ProtocolSupport solved the prefix problem.
Note Java auto-login is broken with ProtocolSupport and #494, but works fine using upstream. EDIT The fork was broken with any Protocol plugin, but I've fixed it.

[t0ssox]

Thanks so much for fixing your fork (autoRegister thing), I wanted to report about this for you but I didn't know where. About Protocol plugins you are right, on ProtocolSupport prefixes works fine but I can't just switch from ProtocolLib to ProtocolSupport because most of my plugins rely on ProtocolLib and doesn't have support for ProtocolSupport (VentureChat, InteractiveChat).

This problem is caused by bad implementation from FastLogin or its ProtocolLib problem mostly?

[Smart123s]

I wanted to report about this for you but I didn't know where.

You can report anything related to he for in it's pull request #494

This problem is caused by bad implementation from FastLogin or its ProtocolLib problem mostly?

I think that either Floodgate or ProtocolLib does something wrong here, because even registering an empty START listener will break the prefixes.