Let’s take your scenario: a proton/anti-proton pair of virtual particles pops into existence from the quantum vacuum near the event horizon and the anti-proton spirals into the black hole, meaning that the proton no longer has it’s antiparticle to annihilate against. (Clearly we’re talking about energy in terms of mass-energy terms here.)
OK, the original virtual-particle pair ‘borrowed’ energy from the vacuum; that debt must be paid back because the universe’s energy must be conserved. If the energy can no longer be ‘returned’ by annihilating the virtual particles, the ‘energy debt’ must be subtracted from the mass-energy of the black hole. This, essentially, is the process of Hawking radiation that causes a black hole to evaporate: it’s kind of like cosmic repo-men demanding dues from the black hole. The universe wants to be made whole and it gets it’s due from wherever it can. If the repo-men can’t find you and repossess your unpaid television, they annoy your old folks instead.
Here’s where the quantum-information question arises: is there any ‘information’ contained in that debt repayment? The classical view says ‘no’: it’s just the right amount of mass-energy, but all other parameters are random (spin, charge, bla bla bla). Quantum mechanics cannot accept that and insists that the information must be expressed as energy radiating with exactly the right characteristics. As if the dollars extracted from your parents must also, in some sense, carry a hint of that TV you haven’t paid for.