According to the current understanding of theoretical physics, black holes do not destroy matter when they are evaporating. Instead, they undergo a process called Hawking radiation, which leads to their gradual loss of mass and energy over time.
Hawking radiation is a theoretical prediction made by physicist Stephen Hawking in 1974. It arises due to a combination of quantum mechanics and the properties of black holes. According to quantum field theory, particle-antiparticle pairs are constantly being created and annihilated in empty space. Near the event horizon of a black hole, one particle from such a pair can fall into the black hole while the other escapes into space, resulting in a net loss of mass for the black hole.
Over time, this process causes black holes to emit energy in the form of particles, including photons, electrons, and other particles, collectively known as Hawking radiation. The rate of Hawking radiation emission increases as the black hole's mass decreases, and as a result, smaller black holes are expected to evaporate more quickly than larger ones.
While Hawking radiation represents a theoretical mechanism for black hole evaporation, it is important to note that this process is extremely slow for astrophysical black holes. The timescale for the evaporation of a black hole with the mass of a typical star is many orders of magnitude longer than the current age of the universe. Therefore, the complete evaporation of black holes has not been observed or confirmed experimentally.
In summary, black holes do not destroy matter when they are evaporating through Hawking radiation. Rather, they gradually lose mass and energy over an extremely long timescale.