I learned this from a French researcher Jean-Pierre Petit who is not supported by the French academy because he goes against the idea of black holes and dark matter by proposing an alternative model which would make all the papers that have been produced for several decades on this subject are obsolete, putting an end to the income that many scientists enjoy for following the mainstream doxa. Despite the lack of support, his model looks both simpler and gives more observational confirmation. It's been +70 years of research in cosmology that leads to nothing, the simple concept of "dark" matter / energy only serves to justify inconsistencies between observed reality and the LambdaCDM model (mainstream) The presentation of the videos and of his site are a bit "artisanal" because he does almost everything himself. If you look carefully on his site, all these papers are public and verifiable (higher math level) Long video on black hole : https://www.youtube.com/watch?v=RKmxVKINk8A

English video series : https://www.youtube.com/playlist?list=PLfdj8oy5zeoHJohMx_VLaK0-2_A_TQrKB

Video against the inflation (of the universe) : https://www.youtube.com/watch?v=IaSQPD_nR6A

Researcher's site with cosmology paper : https://www.jp-petit.org/papers/cosmo/

Articles (most have been translated into English) : http://www.savoir-sans-frontieres.com/JPP/telechargeables/free_downloads.html#english

it's a difficult subject, if cosmology doesn't interest you, it may not be an accessible rabbit hole.