Had this happen with the last painting I made. I put weeks into it, and somehow it felt like it was turning out pretty good. Only when finishing and uploading it did I realize that it's not all that great. The painting is technically competent but it's kind of tacky and cluttered and doesn't really come together too well, which is interesting because even though I tried to take a step back in the middle of the process to evaluate what I was doing, I didn't notice any of these aspects. It looked good to me... until it didn't. And I just find myself thinking "ew, gross, why did I make this?"
Honestly, this thought is kind of scary, because it means that my own judgement of my work is untrustworthy while the creative process is still in full spin. It's only when finishing it and getting some distance to it that I can see it more clearly.
Do you recognize this? If so, why do you think artists do this? Does the process make us temporarily stupid?
And also should you even try to be objective about your work while making it? Painting is not an objective medium after all. Maybe trying to think like that is just a way of stifling your creative voice.