Max players are ignored if many players are connecting at the same time

Expected behavior

If the server reaches the maximum of players, all other players should be disconnected.

Observed/Actual behavior

e.g. i send 4 players on a velocity server onto another backend server with maximum of 2 players, all 4 players can connect.

Steps/models to reproduce

Setup a network with velocity and two backend servers
set the maximum players of the other server than the lobby to e.g. 2
send more than 2 players to the backend server with the maximum players of 2

Plugin and Datapack List

[00:11:37] [Server thread/INFO]: Server Plugins (8):
[00:11:37] [Server thread/INFO]: Paper Plugins:
[00:11:37] [Server thread/INFO]: - SignedVelocity
[00:11:37] [Server thread/INFO]: Bukkit Plugins:
[00:11:37] [Server thread/INFO]: - CloudNet-Bridge, FastAsyncWorldEdit, PacketWrapper, ProtocolLib, spark, ViaBackwards, ViaVersion
[00:11:39] [Server thread/INFO]: There are 2 data pack(s) enabled: [vanilla (built-in)], [file/bukkit (world)]
[00:11:39] [Server thread/INFO]: There are no more data packs available

Paper version

[00:11:10] [Server thread/INFO]: This server is running Paper version git-Paper-496 (MC: 1.20.4) (Implementing API version 1.20.4-R0.1-SNAPSHOT) (Git: 7ac24a1 on ver/1.20.4)
You are running the latest version

Other

No response

Reproduce the issue using Velocity and two backend servers, configuring one backend with a two-player maximum and sending more than two players to it. Trace the server's player-connection handling to determine why simultaneous connections exceed the configured limit; done means excess players are disconnected reliably under concurrent connections.