Ditto. In my case it's just that the amount of work I would have to do to be happy with my own side projects causes me to procrastinate on starting them, as I don't have a perfect image in my head of an objectively successful outcome yet so I just delay.
The way you put this really resonates with me. Often when I'm procrastinating it's because a task seems/feels/sounds really daunting, but the "daunting" feeling is because I'm imagining just how damn hard it's going to be to do the task perfectly. It creates this mental barrier to getting started because completing it perfectly (or, to my expectations) seems too hard.
Breaking out of this by realizing that "perfect" is not the goal, and setting more attainable sub-goals for myself is key, but hard.