MODEL PROBLEMS. “The standard cosmological model, ΛCDM, has been very successful. But aside from the fact that dark matter particles have not been (directly) detected, this model suffers some noticeable shortcomings, such as missing satellite problem, core/cusp problem, too-big-to-fail problem, to name just a few.” (ΛCDM = the standard cosmological model).
https://www.mdpi.com/1099-4300/21/11/1035/htm