yea you can change the server.properties line that allows flight anymore and turn that off. then turn on force gamemode and that should take care of your server. it will kick people that fly and everytime someone logs in their game mode will be set to survival and will not have fly unless your players have the command for it.. if youre having problems with poeple hacking or something and flying everywhere then youre going to need to go grab a plugin like NocheatPlus or even world guard and a multiworld plugin like i use its called myworlds that will force people to not fly and stay in survival indefinitely
How did you do this? I'm guessing the "spam problem" is caused by this..
yea pretty sure its a spam file or auto command that will execute the essentials command /fly <name> and turn it off for whoever has it. which mean sit is essentials spamming the console. here is another way to do it. give yourself and everyone that doesnt want to see this fly spam this permission
or it may be the other way around
if that still works it will not spam you or anyone else anymore not sure if that one still works. it also will not give anyone any notifications at all anymore as well though. like teleports and /tpa dn gamemodes bans nothing. it will turn it all off. so im not sure if you really want to do that. could be why they couldve gotten rid of it