I’m also puzzled by the fact that Hubble can see anything at all at that distance. There a two reasons for my saying this: Firstly the Hubble Redshift with distance relationship should shift the narrow optical band down into the low infra red bands or even the top end of the RF bands. The SKA low frequency array is intended to detect the 1420 MHz hydrogen lines red-shifted to approximately 100 MHz, applying that ratio to the optical regime results in the Hubble scope trying to detect 7 micron infra red, where have I gone wrong? Could be electrons scatter RF more than light?
Secondly the attenuation in the IGM is always ignored. I expect about 200 dB (10^20) of attenuation in the optical spectrum due to scattering off electrons, protons, carbon and iron particles, often referred to as dust. The effective capture area of coulomb charges (electrons, protons) are enormously greater than their physical area, admittedly they mainly have a large area at RF much less so at optical. All my statements are qualitative because the hard knowledge base on attenuation in the IGM has never been studied up until very recently. Those who have studied it have been ridiculed, “the tired light group”, Zwicky, Reber, Hoyle, Arp, Alfen, Lerner, to name a few crackpots. Dust in the IGM is a strong contender for dark matter in this crackpots opinion.