Thx for the good question!

I think that my observation of the existence arbitrary decisions is that as living things we interrupt randomness and cause things to behave in ways that are not the product of free physical mechanics, but the product of what is going on in our minds.

Here we come back to the "what goes on in our minds is also the product of physical processes" argument, and I agree, only that it seems not determined, but "decided".

The fact that I use the word "seems" confirms that it might be an illusion too.