https://pubmed.ncbi.nlm.nih.gov/18408715/ (full paper can be found on SciHub)

> There has been a long controversy as to whether subjectively 'free' decisions are determined by brain activity ahead of time. We found that the outcome of a decision can be encoded in brain activity of prefrontal and parietal cortex up to 10 s before it enters awareness. This delay presumably reflects the operation of a network of high-level control areas that begin to prepare an upcoming decision long before it enters awareness.

This is unfortunately only a brief for Nature Neuroscience -- from 2008, so take with a grain of salt -- and I haven't been able to find the full paper. I also would hesitate to claim this as "lack of free will" or similar; the conclusion sentence from the brief seems to be most-accurate:

> Thus, a network of high-level control areas can begin to shape an upcoming decision long before it enters awareness.