Redshift quantization
There's a pretty comprehensive wikipedia page on the subject. In summary....

Throughout the 2000's conflicting results were published using the same data. The conflict seems to center on the selection effects of the surveys, and the corrections applied to account for them. I did a quick search for 'redshift quantisation' on the Arxiv and found no papers since 2009, which suggests the supporting data has been comprehensibly discredited, or explained away by natural mechanisms.

There are two explanations for the quantization that do not require exotic cosmologies. The first is the large scale clustering of galaxies that traces the cosmic web. The walls and filaments formed in this web leads to groupings of galaxies around specific redshifts along the line of sight. The second explanation is the quantisation of emission from Hydrogen, known as the Lyman series. Since photons can only be released with certain energies, the measured redshifts are also quantised (this is only true in low pressure and temperature environments, otherwise pressure and thermal broadening occur).