The brain is genetically programmed, evolution made it to adapt to the environment. We cannot control our thoughts, decisions. Many decisions have been proven by empiricism that we chose are conditioned to our biological program. The rest of the decisions have not yet proven that 'it is not us'. The same brain that makes decisions 'without us' is the one that thinks, is conscious, rationalizes about what happens. Is that brain not us? It is us, we are just not in control. That our brain is programmed in a way does not limit our freedom. It is still us. It's our brain. It was 'free' when it was not adapted. You are still being a human, free. It does not confront with the concept of being free. There cannot not be determinism. ('Rest' of decisions we make).
Because the brain thinks about the brain, we will never 'govern' it. It is just us.
We can only 'rationalize'. This is, construct a narrative of what happens, only after!. But 'we' (the consciousness) does not stop and make decisions (as it stops now when thinking). It is our brain that does act. What we do is all 'rational', as we were adapted for it. We survived thanks to it. It is just that the environment changed. All we do is rational with survival and reproduction. You are not irrational, just biased, with limits to knoeledge, processing power. Like a monkey.
Biologically programmed and evolved adapted, you are always going to be biased and limited in thinking, deciding. Only very few times you can try and be 'rational', empirical... taming your biology. So if you are your brain (you cannot escape, dissociate from it), as you cannot escape reality's determinismn, you are 'not free'. This is, it is all deterministic. If we can be conscious of our maladaptation, biological programming, make experiments... it means our consciousness is like a spectator. It is 'free', but trapped, isolated, helpless.