There are minceraft versions where you can use cheats to write colored signs or even commands onto signs cause a check is missing.
1.8 -1.8.3 allow for that and also 1.12 as far as I know. But its patched by spigot/bukkit. So it only works on vanilla servers.
And the anticheat thing, although the anticheat is bad, it can still detect you if your settings is too ez to detect (like killaura 7 block range lmfao), or maybe staff banned you but you just don't know that