I've posted this before, but this is a known bug. It would help if everyone could upvote the bug report:

https://bugs.mojang.com/browse/MC-92916

There is a suggestion that these are cause by teleportating between chunks that can be unloaded. It seems to me that people are more often invisible since warps were added, which do teleport you between unloadable (definitely a word) chunks so there might be something to it.
@CraftyMyner do you think it would be worth changing warps so they send you first to spawn, then to the warp, to see if makes a difference to how often players become invisible etc.?

@TheDunmerRaven Ouch, that's mean. It'd also cause lag for the rest of the server though. If you're feeling masochistic you could place a few thousand leaves around your base. Leaves are notoriously bad for fps in large amounts but won't affect the server lag.

@TheSpiderman2013 Do we really need it back? It's easy to tell when the server is lagging, do we gain anything from actually seeing the tick rate? Besides the inevitable chat spam, and potentially more lag from running the command (like Bobcat said).

Have you tried using slime blocks to launch potions or even mobs into the air at them?
It's pretty impractical but it sure would be funny to see a bunch of skeletons get launched at you as you're flying along!

@_Haxington_ nah it asked me to name 3 tamable mobs and like Crafty I wasn't sure how to spell Ocelot, so I wrote Wolf, Horse, Donkey. Apparently that was wrong.

9/10 on the general because apparently donkeys aren't tamable mobs...
Nailed the rest

@NutjobBob @GrinningBobcat I gave you the answer already I think :)

@NutjobBob - Fil

*ahem*
Although according to the wise and all knowing internet it apparently should be "Fille" for stars.

@GrinningBobcat I gave you the answer already I think :)

Fair warning, any overworld mob grinder that doesn't use a spawner is going to have terrible rates on the server. We're talking like 1 drop every 10 minutes if you're lucky. It's probably not worth your time and effort.

@HaloNest You've got the words but you've lost all the aesthetics in the translation my man.

Over fire and over stone,
Over water and over bone
Shining like a jewel of light
On a sheet of purest night

- Fil