Here is the code for cvars.Number - https://github.com/Facepunch/garrysmod/blob/784cd57576d85712fa13a7cea3a9523b4df966b0/garrysmod/lua/includes/modules/cvars.lua#L121
It is shown that cvars.Number uses GetConVarNumber.
On the Wiki,
GetConVarNumber is deprecated, but
cvars.Number is not. So, why is cvars.Number using a deprecated function, but is not deprecated itself?