in popular science, the concept that information is lost beyond the black hole's event horizon is put forward.
But we know that black holes also have a mass, which is a type of information, and they can grow through an accretion disc. Let's assume that a black hole swallow a proton: then the mass of the black hole has increased 10^-27 kg (that is considering negligible any energy dissipation in the process of swallowing mass). In other words the information regarding the mass of the proton is not lost but transferred to the black hole.
So is the concept of loss of information within a black hole a myth? Is the reality more complex?
And if mass can be maintained, are there other physical characteristics that are kept within a black hole? For instance, the Hawking radiation implies that black holes have a temperature, that is thermodynamic information. And they radiate X-ray thus they have an electromagnetic information.