Chat Validation Error while using Velocity and Version 1.20.4

Expected behavior

Players to chat and then run commands without being kicked.

Observed/Actual behavior

Players typing in chat, then run a command and it fails to validate message acknowledgements, resulting in kicking them from the server. Even lowered from Purpur (a fork of paper) down to paper, and velocity to a lower version before 1.20.6 support. Issues still persist.

Steps/models to reproduce

Use Velocity and Paper Version 1.20.4 to type in chat at least twice, then run a command like gamemode spectator.

Plugin and Datapack List

Started with a lot of plugins, eventually moved all of them away to try to fix the issue. Result was same issue.

Paper version

Paper:
[00:17:34 INFO]: Checking version, please wait...
[00:17:35 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
Previous version: git-Purpur-2176 (MC: 1.20.4)

Velocity:
[00:06:52 INFO]: Booting up Velocity 3.3.0-SNAPSHOT (git-be678840-b378)

Other

I have been trying to work on this issue for 3 full days. I usually use Purpur due to my server using features like 6 row enderchests. I dropped it down to Paper to see if this issue kept happening. This issue could be on either Paper or Velocity's side. It only happens on version 1.20.4. I switched from Bungeecord forwarding to modern, changed all the server configs, even deleted them all and moved plugins away, and the issue stayed. I joined from local IP and domain both to test.

Start by reproducing the issue with Paper 1.20.4 and Velocity 3.3.0-SNAPSHOT, using the stated chat-then-gamemode sequence. Review the validation and kick output from both servers, then determine whether the behavior remains with plugins removed and whether it belongs to Paper or Velocity. Done means chat and commands work without message-acknowledgement kicks.