UA is an attempt to align relativity with FE. But if you follow the logic, it turns out to be another pointless mathematical model that has no meaning in reality.
If you believe relativity, you believe we are in a reference frame from which all observation will be defined. Meaning, you cannot look outside your reference frame to see what the external frame would see when it observes your reference frame.
Therefore, we could be moving at any speed in the external reference frame, and not know it. I realize UA theorizes that the speed is ever increasing, and I have no argument against that point.
It may well be ever increasing, and we have no means to confirm or deny that point. The very fact that it cannot be tested in any way is itself the problem. Why should we assume that being pulled down necessarily means that UA is the only explanation?
For example, the outer reference frame could be moving at any constant or increasing speed within yet another external reference frame. We could be in a Russian doll of infinite reference frames. These mathematical models offer infinite possibilities, none of which can be experienced by humans ever.
The appropriate answer to why we are pulled down is "I don't know, but as soon as we can create a compelling experiment, we'll let you know".
Creating more mathematical models that inherently cannot be tested is just as useless as the RE theories.