Muller's ratchet

https://pubmed.ncbi.nlm.nih.gov/34791206/

Muller's ratchet is a process in which deleterious mutations are fixed irreversibly in the absence of recombination. The degeneration of the Y chromosome, and the gradual loss of its genes, can be explained by Muller's ratchet.

http://evolutiongenetics.georgetown.edu/simulations/mullers/

Mutation, genetic drift and natural selection acting at the same time can result in the progressive increase in the number of mutations in a population of a species that is haploid and does not experience recombination. This phenomenon is called Muller’s ratchet.