Garry's Mod, is still to this day an insanely popular game.
There are very few developers who still dedicate their time to the game, as a large majority of cheat sites that do support it use LUA based scripts.
This is at times overall very risky and something Garry (The GMOD coder) has caught frequently and with great ease.
Royal Hack has been around for over 16 years now and they do their very best to ensure the safety of their members, if something breaks they fix it and they do develop improvements all the time.
Currently, with the Launch of CS2 & TF2's new expansion and game mode. Dev's are hard at work upgrading those, but fear not at this point in time the Garry's Mod cheat isn't going anywhere and they still support very old games.
Like the Left 4 Dead franchise, Counter-Strike:Source and Day of Defeat:Source. So it certainly shows their dedication to the games they currently offer cheats for.