The most popular FPS unlocker for Roblox does not modify anything that is protected by Roblox’s memcheck and other security measures, such as the Roblox Luau VM, etc.
It does not inject any files, such as any DLL files, but instead just modifies program memory.
Therefore, you’re safe to use this as you won’t be banned by Roblox and in my previous reply, Roblox made a personal promise to not ban anyone for it.