Does cosmological isotropy imply a special frame of reference?

I'm asking as someone who is relatively knowledgeable in the particle physics side of things but only just dipping my toes into cosmology.

I understand that in cosmology there's the assumption of isotropy, that the distribution of galaxies in space does not depend on any particular direction. At first glance, this seems like an entirely reasonable assumption.

However now assume this assumption is true in reference frame A, and consider reference frame B that is Lorentz-boosted in direction X. From B's perspective, would it not appear that the galaxies are much closer together in direction X, compared to any orthogonal direction due to length contraction? Thus there appears to be only a single reference frame A in which this grand assumption of isotropy is actually true. This seems to contradict the relativistic philosophy of all reference frames being equally special. Am I missing something here?