• [X ] This issue is not solved in a development build

Describe the bug
During login and logout from the server, I'm getting errors. Also sometimes when a user logs in they are getting disconnected, I wasn't sure it was ProtocolLib, but I started getting errors upon logout as well that specifically mention ProtocolLib. Since the login errors mention protocols and netty. I thought I would also mention it here to see if they are related. It's beyond my scope, if it's unrelated to ProtocolLib, hopefully you will be able to point me in the right direction. Thank you for your time and your assistance.
I know it mentions, Antipopup. I also reached out to them to see if it's their plugin messing up Protocollib, or the other way around. Just to cover my bases.

Console16:51:10 at io.netty.channel.DefaultChannelPipeline.writeAndFlush(DefaultChannelPipeline.java:1020) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.AbstractChannel.writeAndFlush(AbstractChannel.java:311) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at ProtocolLib.jar/com.comphenix.protocol.injector.netty.channel.NettyChannelProxy.lambda$writeAndFlush$1(NettyChannelProxy.java:223) ~[ProtocolLib.jar:?] at ProtocolLib.jar/com.comphenix.protocol.injector.netty.channel.NettyChannelProxy.lambda$processPacketOutbound$2(NettyChannelProxy.java:266) ~[ProtocolLib.jar:?] at ProtocolLib.jar/com.comphenix.protocol.injector.netty.channel.NettyChannelProxy.processPacketOutbound(NettyChannelProxy.java:268) ~[ProtocolLib.jar:?] at ProtocolLib.jar/com.comphenix.protocol.injector.netty.channel.NettyChannelProxy.writeAndFlush(NettyChannelProxy.java:223) ~[ProtocolLib.jar:?] at ProtocolLib.jar/com.comphenix.protocol.injector.netty.channel.NettyChannelProxy.writeAndFlush(NettyChannelProxy.java:233) ~[ProtocolLib.jar:?] at net.minecraft.network.Connection.doSendPacket(Connection.java:504) ~[purpur-1.20.6.jar:1.20.6-2217-2842b97] at net.minecraft.network.Connection.sendPacket(Connection.java:486) ~[purpur-1.20.6.jar:1.20.6-2217-2842b97] at net.minecraft.network.Connection.send(Connection.java:448) ~[purpur-1.20.6.jar:1.20.6-2217-2842b97] at net.minecraft.network.Connection.send(Connection.java:434) ~[purpur-1.20.6.jar:1.20.6-2217-2842b97] at net.minecraft.network.Connection.exceptionCaught(Connection.java:220) ~[purpur-1.20.6.jar:1.20.6-2217-2842b97] at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:346) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:325) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:317) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.ChannelHandlerAdapter.exceptionCaught(ChannelHandlerAdapter.java:92) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at AntiPopup-8.1.jar/com.github.kaspiandev.antipopup.libs.packetevents.injector.handlers.PacketEventsEncoder.exceptionCaught(PacketEventsEncoder.java:128) ~[AntiPopup-8.1.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:346) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:325) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:317) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.ChannelInboundHandlerAdapter.exceptionCaught(ChannelInboundHandlerAdapter.java:143) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at AntiPopup-8.1.jar/com.github.kaspiandev.antipopup.libs.packetevents.injector.handlers.PacketEventsDecoder.exceptionCaught(PacketEventsDecoder.java:69) ~[AntiPopup-8.1.jar:?] at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:346) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:325) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:317) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.handler.flush.FlushConsolidationHandler.exceptionCaught(FlushConsolidationHandler.java:159) ~[netty-handler-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:346) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:325) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.AbstractChannelHandlerContext.fireExceptionCaught(AbstractChannelHandlerContext.java:317) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.DefaultChannelPipeline$HeadContext.exceptionCaught(DefaultChannelPipeline.java:1377) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:346) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.AbstractChannelHandlerContext.invokeExceptionCaught(AbstractChannelHandlerContext.java:325) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.DefaultChannelPipeline.fireExceptionCaught(DefaultChannelPipeline.java:907) ~[netty-transport-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.handleReadException(AbstractEpollStreamChannel.java:728) ~[netty-transport-classes-epoll-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:826) ~[netty-transport-classes-epoll-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.epoll.EpollEventLoop.processReady(EpollEventLoop.java:509) ~[netty-transport-classes-epoll-4.1.97.Final.jar:4.1.97.Final] at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:407) ~[netty-transport-classes-epoll-4.1.97.Final.jar:4.1.97.Final] at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[netty-common-4.1.97.Final.jar:4.1.97.Final] at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.97.Final.jar:4.1.97.Final] at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]

The second error only shows when a user tries to login... they have to try 2-3 times before it lets them in. Any thoughts are appreciated if it's not related to ProtocolLib.
14:55:04 UUID of player USER is UUID 14:55:05 com.mojang.authlib.GameProfile@25764f73[id=UUID,name=USER,properties={textures=[Property[name=textures, value=ewogICJ0aW1lc3RhbXAiIDogMTcxNjgzOTUwNjYwNCwKICAicHJvZmlsZUlkIiA6ICI3YTJjZGVlNGNiMTE0OWI3OGNjNzI0ZDE0ZDg3MjIzOSIsCiAgInByb2ZpbGVOYW1lIiA6ICJSZWFwZXJSb3NlMTIwMCIsCiAgInNpZ25hdHVyZVJlcXVpcmVkIiA6IHRydWUsCiAgInRleHR1cmVzIiA6IHsKICAgICJTS0lOIiA6IHsKICAgICAgInVybCIgOiAiaHR0cDovL3RleHR1cmVzLm1pbmVjcmFmdC5uZXQvdGV4dHVyZS80MzJmNjQ0MWYzMmY2OGM2MjQyNmE5N2EzOTdkODFiZWE3MjA3OGM1ZTliMWUyOGZiODhiMzY5YjYzNGIwYWY3IgogICAgfQogIH0KfQ==, signature=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]]}]: lost connection: Internal Exception: io.netty.handler.codec.EncoderException: Pipeline has no outbound protocol configured, can't process packet net.minecraft.network.protocol.common.ClientboundKeepAlivePacket@7e5de046

To Reproduce
Steps to reproduce the behavior:
Happens randomly, but seems to be isolated to Logins and Logouts.

Expected behavior
No console errors?

Screenshots

Version Info
Purpur Version: 1.20.6-2217-2842b97 (MC: 1.20.6)*
ProtocolLib Version: ProtocolLib v5.2.1-SNAPSHOT-689
https://pastebin.com/wUdgdJ7u

Additional context

Also getting a similar issue.
https://pastebin.com/LgkSeanS