can exploiters take advantage of OnClientEvent to fire to all players?

this might be a dumb question but i just wanna make sure

i was wondering if i did fireallClients on the server and the OnClientEvent gets the signal can exploiters just use that OnClientEvent to fire to all players or is it just them that can see whats going on

im doing something like this

--Client
RemoteEvent:FireServer()

RemoteEvent.OnClientEvent:Connect(function()
--do something
end)

--Server
RemoteEvent.OnServerEvent:Connect(function()
RemoteEvent:FireAllClients()
end)