If fabric/velocity is setup with modern forwarding (may happen on other types) with fabric-api installed some entities and items become randomized to the client, item frames become broken you are unable to drop items all sounds become mixed up among other things...
Examples:
Tier 3 rocket:
![image](https://user-images.githubusercontent.com/39572468/82843835-b3b00c00-9e9b-11ea-86e3-78074246a9fb.png)
[15:11:29] [main/INFO]: Loading for game Minecraft 1.15.2
[15:11:30] [main/WARN]: Mod `fabricproxy` (1.3.0) uses 'requires' key in fabric.mod.json, which is not supported - use 'depends'
[15:11:30] [main/WARN]: Mod `autoconfig1` (1.2.0+mc1.14.4) uses 'requires' key in fabric.mod.json, which is not supported - use 'depends'
[15:11:30] [main/INFO]: [FabricLoader] Loading 39 mods: [email protected], [email protected], [email protected]+f08b61330c, [email protected]+e08a73050c, [email protected]+dfdb52d60c, [email protected]+2aebb7ff0c, [email protected]+build.198, [email protected]+3e5587510c, [email protected]+9290e2ed0c, [email protected]+b7f9825d0c, [email protected]+2ad156310c, [email protected]+3e5587510c, [email protected]+3b05f68e0c, [email protected]+b7f9825d0c, [email protected]+fac69e320c, [email protected]+b7f9825d0c, [email protected]+534104900c, [email protected]+2a034f0a0c, [email protected]+b7f9825d0c, [email protected]+06c939b30c, [email protected]+821cdba70c, [email protected]+b7f9825d0c, [email protected]+abd915800c, [email protected]+12515ed90c, [email protected]+2e0c4ff50c, [email protected]+f3d8141b0c, [email protected]+mc1.14.4, [email protected]+c6a8ea890c, [email protected]+ec951ea40c, [email protected]+6ffe71e20c, [email protected]+5a0f9a600c, [email protected]+003643510c, [email protected]+e08a73050c, [email protected]+build.310-1.15, [email protected]+ad2f81bd0c, [email protected]+045efb460c, [email protected]+dfdb52d60c, [email protected]+3e5587510c, [email protected]+003643510c
[15:11:30] [main/INFO]: SpongePowered MIXIN Subsystem Version=0.8 Source=file:/home/minecraft/serverfiles/minecraft_server.jar Service=Knot/Fabric Env=SERVER
[15:11:39] [main/WARN]: Ambiguity between arguments [teleport, destination] and [teleport, targets] with inputs: [Player, 0123, @e, dd12be42-52a9-4a91-a8a1-11c01849e498]
[15:11:39] [main/WARN]: Ambiguity between arguments [teleport, location] and [teleport, destination] with inputs: [0.1 -0.5 .9, 0 0 0]
[15:11:39] [main/WARN]: Ambiguity between arguments [teleport, location] and [teleport, targets] with inputs: [0.1 -0.5 .9, 0 0 0]
[15:11:39] [main/WARN]: Ambiguity between arguments [teleport, targets] and [teleport, destination] with inputs: [Player, 0123, dd12be42-52a9-4a91-a8a1-11c01849e498]
[15:11:39] [main/WARN]: Ambiguity between arguments [teleport, targets, location] and [teleport, targets, destination] with inputs: [0.1 -0.5 .9, 0 0 0]
[15:11:40] [Server thread/INFO]: Starting minecraft server version 1.15.2
[15:11:40] [Server thread/INFO]: Loading properties
[15:11:40] [Server thread/INFO]: Default game type: SURVIVAL
[15:11:40] [Server thread/INFO]: Generating keypair
[15:11:40] [Server thread/INFO]: Starting Minecraft server on 127.0.0.1:30067
[15:11:40] [Server thread/INFO]: Using epoll channel type
[15:11:41] [Server thread/WARN]: **** SERVER IS RUNNING IN OFFLINE/INSECURE MODE!
[15:11:41] [Server thread/WARN]: The server will make no attempt to authenticate usernames. Beware.
[15:11:41] [Server thread/WARN]: While this makes the game possible to play without internet access, it also opens up the ability for hackers to connect with any username they choose.
[15:11:41] [Server thread/WARN]: To change this, set "online-mode" to "true" in the server.properties file.
[15:11:41] [Server thread/INFO]: Preparing level "world"
[15:11:41] [Server thread/INFO]: [fabric-registry-sync] Loaded registry data [file 1/4]
[15:11:41] [Server thread/INFO]: Reloading ResourceManager: Default, Fabric Tool Attribute API (v1)
[15:11:55] [Server thread/INFO]: Loaded 6 recipes
[15:11:56] [Server thread/INFO]: Loaded 825 advancements
[15:11:56] [Server thread/INFO]: Preparing start region for dimension minecraft:overworld
[15:11:57] [Server thread/INFO]: Preparing spawn area: 0%
[15:11:57] [Server thread/INFO]: Preparing spawn area: 0%
[15:11:57] [Server thread/INFO]: Preparing spawn area: 0%
[15:11:57] [Server thread/INFO]: Time elapsed: 1549 ms
[15:11:57] [Server thread/INFO]: Done (16.830s)! For help, type "help"
[15:11:57] [Server thread/INFO]: Starting GS4 status listener
[15:11:57] [Query Listener #1/INFO]: Query running on 127.0.0.1:25565
[15:16:06] [Server thread/INFO]: CGDoctor8[/192.168.1.149:33092] logged in with entity id 225 at (30.83925180212744, 64.0, 10.057062025113616)
[15:16:06] [Server thread/INFO]: CGDoctor8 joined the game
[15:22:01] [Server thread/INFO]: [CGDoctor8: Set own game mode to Spectator Mode]
[15:23:16] [Server thread/INFO]: [CGDoctor8: Teleported CGDoctor8 to 0.5, 70.0, 0.5]
[15:23:16] [Server thread/WARN]: CGDoctor8 moved too quickly! 183.4162979550047,-39.545352872898135,277.13674201765576
[15:23:16] [Server thread/WARN]: CGDoctor8 moved too quickly! 183.4162979550047,-39.545352872898135,277.13674201765576
[15:24:22] [Server thread/INFO]: [CGDoctor8: Set own game mode to Creative Mode]
[15:24:22] [Server thread/INFO]: [CGDoctor8: Set own game mode to Spectator Mode]
[15:24:24] [Server thread/INFO]: [CGDoctor8: Set own game mode to Creative Mode]
[15:24:40] [Server thread/INFO]: [CGDoctor8: Set own game mode to Spectator Mode]
[15:25:12] [Server thread/INFO]: [CGDoctor8: Set own game mode to Creative Mode]
[15:25:23] [Netty Epoll Server IO #1/ERROR]: io.netty.handler.codec.EncoderException: String too big (was 353289 bytes encoded, max 262144)
[15:25:37] [Server thread/INFO]: [CGDoctor8: Set own game mode to Spectator Mode]
[15:25:45] [Server thread/INFO]: [CGDoctor8: Summoned new Creeper]
[15:25:49] [Server thread/INFO]: [CGDoctor8: Summoned new Skeleton]
[15:25:57] [Server thread/INFO]: [CGDoctor8: Summoned new Enderman]
[15:26:52] [Netty Epoll Server IO #1/ERROR]: io.netty.handler.codec.EncoderException: String too big (was 353289 bytes encoded, max 262144)