PreventExcessiveFireworkExploit - dniym/IllegalStack GitHub Wiki
ON BY DEFAULT - MC 1.13
Detects fireworks which have an excessive number of effects and removes the effects, an exploit exists in 1.13 that allows players to create specially crafted fireworks that will lag / crash the server.
To enable / disable this protection use the following command: /istack toggle PreventExcessiveFireworkExploit
This protection has no extra options.