Both determinism and free will are flawed concepts.

The problem is that as mobile organisms, our sentience coalesces as a sequence of perceptions in order to navigate, so our concept of time is as the point of the present, moving past to future, cause leading to effect.

Yet the reality is that change turns future to past. Tomorrow becomes yesterday, because the earth turns. There is no dimension of time, because the past ic consumed by the present, to inform and drive it. Conservation of energy and causality. Cause becomes effect.

So the act of determination can only occur as the present and we are part of nature's process of selection.

As for free will, the premise of will is to affect and without cause, there is no effect, so it's an oxymoron.