So, in our reference frame, black holes never grow from original collapse and remain in that same state, tiny mass and size, no matter what falls into it. Wait, no. It loses mass through particle emission, which is assumed to actually happen. This puzzle was worth investigating when I learned this topic (not sure I understood all math and concepts correctly though).
I mean, the real answer is "black holes are very complicated" and a full explanation is out of scope for a HN comment. Hawking radiation requires a lot of background knowledge to understand (and I have to admit I still don't fully understand it). The pop-sci explanation of particle/anti-particle pairs appearing on either side of the event horizon is incorrect.