It was in the preprint study itself. There were only 26 total mice enrolled in the 14-day mortality stage of the study, spread out against the wild-type, omicron-s and omicron. Looks like media is extrapolating this small study on mice into human fear porn. In mice, in this tiny study, it seems to confirm omicron is mostly meaningless and omicron-s is stronger but not as lethal to mice as the original WT.
How could 26 mice divided into three groups to test three variants confirm anything about anything? That is only 8.6 mice per variant.