Why is the spectator bug fixed (and can I make it work again)?
When I'm in single player or on a Mojang server, this https://bugs.mojang.com/browse/MC-46503 works. But, when I join a Spigot (or even Bukkit or Paper) server, it's fixed for me. Does anyone know why? I'm really curious
Works on Mojang: https://imgur.com/NAw72Sf
Doesn't on Bukkit/Spigot/Paper: https://imgur.com/bdhIBCs
Also, can make it so the bug works again?
I also asked this question on Spigot here: https://www.spigotmc.org/threads/why-is-the-spectator-bug-fixed-and-can-i-make-it-work-again.564535/
Bukkit, Spigot, etc fix some bugs in vanilla Minecraft (on purpose). In some cases, the underlying logic that created the bug in the first place is entirely replaced (possibly for completely separate reasons) in modified server versions. It is quite likely impossible to "put back" the bug.
If you want the vanilla bugs, use a vanilla server. In fact, anarchy servers often stick to vanilla servers because they want to keep all the vanilla bugs.