The most concise description of the matter antimatter imbalance problem i could find is this one:
Abstract
The matter-antimatter asymmetry problem, corresponding to the virtual nonexistence of antimatter in the universe, is one of the greatest mysteries of cosmology. According to the prevailing cosmological model, the universe was created
in the so-called “Big Bang” from pure energy and it is generally considered
that the Big Bang and its aftermath produced equal numbers of particles and
antiparticles, although the universe today appears to consist almost entirely
of matter rather than antimatter. This constitutes the matter-antimatter asymmetry problem: where have all the antiparticles gone? Within the framework
of the Generation Model (GM) of particle physics, it is demonstrated that the
asymmetry problem may be understood in terms of the composite leptons and
quarks of the GM. It is concluded that there is essentially no matter-antimatter
asymmetry in the present universe and that the observed hydrogen-antihydrogen
asymmetry may be understood in terms of statistical fluctuations associated
with the complex many-body processes involved in the formation of either a
hydrogen atom or an antihydrogen atom.
source:
Robson, B.A.
(201
The Matter-Antimatter Asymmetry
Problem. Journal of High Energy Physics,
Gravitation and Cosmology, 4, 166-178.
https://doi.org/10.4236/jhepgc.2018.41015
That's also what scares me about the "anti-star" concept. In a universe filled with matter and dark matter, such a powerful object would be.... very energetic... when it meets matter, like interstellar dust perhaps.