"Side effect" is perhaps not the right term, since the effect loops back into the processes; evidence for that is that we are talking about consciousness.
https://physicsworld.com/a/why-free-will-is-beyond-physics/
https://aeon.co/essays/heres-why-so-many-physicists-are-wron...
Since when is superdeterminism a done deal?
Conway had a few interesting words on this topic: https://en.m.wikipedia.org/wiki/Free_will_theorem
There is no largely accepted obvious place where free will emerges from, while at the same time superdeterminism is not proven as you say.
So it's fair for some to say that physics as we know it doesn't allow free will, while at the same time it's fair for others to say that obviously they have free will thus it must exist.
How?