I just read Carlo Rovelli's article about what is on the other side of black holes. He asks where does matter go after it falls in the black hole.
I think Einstein gave the answer in 1919 when he published a paper asking if gravitation and electromagnetism play a role in formation of elementary particles. The criticism that his paper doesn't address the two nuclear forces discovered in the 1930s is easily overcome. The gravitational and electromagnetic waves can interact to produce the mass - and via quaternions, the quantum spin - of both massive and massless nuclear bosons.
Referring to the quantum nature of gravity, I think matter that falls in would be dissociated into its component photons (spin 1) and gravitons (spin 2) by the black hole's intense gravity. (Together, a photon and graviton form the spin 1/2 of the original matter particles).
Of course, the quantum spin of 2/1 can also result. This is the spin of gravitons which the falling matter has added, increasing the black hole's gravity.
Just as gravity dissociates the matter, a hypothetical white hole would require an anti-gravitational effect to assemble photons and gravitons into matter that might issue forth.
If the photons and gravitons were not elementary but were composed of the binary digits 1 and 0, information would be preserved when matter entered the black hole. And if matter does issue from a white hole, the information is re-assembled.