Is there any possible ways to display every players game mode on screen such as setdisplay function/command? This would be used so that server OP's did not cheat to get resources that they want.
Create a dummy variable:
/scoreboard objectives add gamemode dummy
In a repeating command block, set their score to 1 if they're in creative:
/scoreboard players set @a[gamemode=creative] gamemode 1 (You'll need to
/forceload the chunk the repeating command block is in.)
And add it to the sidebar:
/scoreboard objectives setdisplay sidebar gamemode
This will show in the sidebar whether someone has entered creative mode, even if they swap back to survival mode afterwards. To reset it, do
/scoreboard players set PLAYERNAME gamemode 0, replacing PLAYERNAME with the name of the player.
There is a very simple way of doing it with a plugin. Make sure you are running Spigot and download the PAPI plugin. Then move it to your plugins folder and restart/start your server.
Once the plugin is loaded, type
/papi ecloud download Player. Then reload using
/papi reload and use the placeholder
%player_gamemode% anywhere you want.