Unknownreported this bug
Plugin sending too many packets because of incompatibility with protocollib. There is my timings https://timings.aikar.co/?id=ce748d3500444f6ebce11249fa639512#plugins Plugins: [Legacy attachment omitted]
When i remove one of the plugins (MCCosmetics or ProtocolLib) it's work like it should.
It's simple to replicate (atleast for me) Just join the server that's all, there is an example video https://youtu.be/1zAq_UQljPM