Player kicked on deop

On a Minecraft server, running the command /deop <name> to deop a player will kick them as if they were kicked for not being whitelisted, as well as deoping them. This issue occurs whether the player is deoped from the console or by themselves (I cannot test if being deoped by another player causes the same behavior, but I expect it would). The screen after being kicked is attached. The server is not whitelisted and the player can join back right after being kicked.