"Indeed, Wilczek began his lecture by speaking of the profound analogy between materials and vacuum. What our naked senses perceive as empty space turns out to be a riotous environment of virtual particles fluorescing and dying away on extremely small scales of space and time, as well as fog-like fields and condensates, which permeate all space and dictate the properties of elementary particles. To give an analogy for this perplexing new picture of reality, Wilczek asks us to imagine intelligent fish in a world surrounded by water. Such creatures would perceive the water surrounding them as their version of empty space or a vacuum. "The big idea I want to convey is simply this: We're like those fish," he said. What our senses perceive as empty space is better understood as a substance, a material." https://asunow.asu.edu/20170208-finding-nothing-conversation-frank-wilczek
Paul Davies: "This leads to the prediction of vacuum friction: The quantum vacuum can act in a manner reminiscent of a viscous fluid." http://philpapers.org/rec/DAVQVN
"Some physicists, however, suggest that there might be one other cosmic factor that could influence the speed of light: quantum vacuum fluctuation. This theory holds that so-called empty spaces in the Universe aren't actually empty - they're teeming with particles that are just constantly changing from existent to non-existent states. Quantum fluctuations, therefore, could slow down the speed of light." https://www.sciencealert.com/how-much-do-we-really-know-about-the-speed-of-light
So it is quite reasonable to assume that, by gradually slowing down the speed of light, "vacuum friction" causes the cosmological (Hubble) redshift, in a non-expanding universe.
Paul Davies: "This leads to the prediction of vacuum friction: The quantum vacuum can act in a manner reminiscent of a viscous fluid." http://philpapers.org/rec/DAVQVN
"Some physicists, however, suggest that there might be one other cosmic factor that could influence the speed of light: quantum vacuum fluctuation. This theory holds that so-called empty spaces in the Universe aren't actually empty - they're teeming with particles that are just constantly changing from existent to non-existent states. Quantum fluctuations, therefore, could slow down the speed of light." https://www.sciencealert.com/how-much-do-we-really-know-about-the-speed-of-light
So it is quite reasonable to assume that, by gradually slowing down the speed of light, "vacuum friction" causes the cosmological (Hubble) redshift, in a non-expanding universe.