I can't answer completely on-topic because I don't believe there's ever been a time where I've seen only flaws in something I've drawn, but generally speaking: when I'm looking back at my work, especially recent work, and keep noticing the same issues surfacing over and over again, I try my best to keep a mental list of the things that are going wrong, and really try to tackle those areas hard.
For example, one area that I've been trying to tackle throughout my current comic is how to render backgrounds better: I've had an issue for a long time where my backgrounds have looked pretty mediocre because even though the basics of perspective were being applied and there were some elements sprinkled throughout (buildings/trees/etc.) there were still lots of large areas of flat color and just tons of empty space in general which looks... not great, usually. So I started really trying to "level up" my backgrounds by making a conscious effort to add a lot more detail and texture into flesh them out better. And the improvements are noticeable. Granted it wasn't over night, but standing here a year later there's so so much progress between pages 60~70 vs. 1~10. And still tons of flaws, yeah, but baby steps.
Similarly when the current season ends on page 70 I'm planning to take a lengthy break to work on a few other big issues that I've noticed started popping up recently- there's a lot of little things about how my faces and anatomy in general have been turning out that's bugging me, so I'm hoping to rectify those at least a little bit before departing on season 2 lol.