Personally it helps me to have a to-do list.
While I’m working on a feature, and notice something else being off (like a placeholder texture, or another feature not working as expected) I’ll add an entry to my list like Look at why X is misbehaving.
Then next time I have free time, I look at the to-do list and have an idea of what needs to be done next.
It might feel weird at first, because you’re a solo dev, and it might feel silly to write things down for your future self, but once you’re in the habit, it helps a lot keep track of at least the majority of issues.