This plugin that I made over the weekend allows administrators and server owners to prevent players from using their Elytra whilst in combat. :)

Important note: OPs by default have the permission nodes to bypass the checks, if you're wondering why it might not be working, try deoping yourself.

Config stuff:

Several values can be customised under NoElytraDuringCombat/settings.yml:

combatTimeInSeconds: How long the combat timer lasts in seconds.

notifyInterval: How long in seconds between each denial message.

Messages can also be customised under NoElytraDuringCombat/lang.yml

Permission nodes:

nedc.bypass: Bypass all checks for testing purposes.

nedc.save: Save all data manually via /save.

nedc.reload: Reload the plugin.

Demonstrated on my YouTube channel: https://www.youtube.com/watch?v=_BgBQcQClWw