Trek has regularly been a champion of individuality, and individuals working together, versus individual personality being subsumed under cultural or physiological uniformity. At the same time, it has always had a kind of antagonistic relationship with many elements of transhumanism, or changing biology in many ways — genetic, cybernetic, and arguably even ideological (you do not leave the federation nor abandon its ideals, and species tend to stick to homogenous patterns within it) with few exceptions. These Changelings are heretics twice over essentially, they have rejected their Dominion status, and not even to come closer to the federation, and they have adjusted their physiology. To be fair, that was initially something done to them, by elements in the federation. Later they did it to themselves as others joined. But that makes them into something pitied essentially. This is on top of the thing that Odo, and presumably other shapeshifters have had to deal with — explaining why many other shapeshifting races keep it secret, and even the Trill keep what amounts to personality shapeshifting mostly secretive for a long time— which is a sort of uncanny valley effect when dealing with non-malleable races. I do not think their status as shapeshifters this season was commentary — except in a very traditional ‘reds under the bed’ way — but their status as changelings were. They are the soldiers of the last war, mistreated by the victors, rejected by their own society. Led by zealotry, and given to brutality. I’ve said it before, but these guys are basically Isis or Daesh Changelings. Radicalised, and now buddied up with the other ‘old enemy’. You could even argue the Borg Queen is Putin, I suspect.