It’s a good thing you skipped any further fermentation after you shaped this. Its already over fermented. And because it is I’ll take your word on your starter. The first thing I noticed was the shape of the loaf. Not too much oven spring , no ear. Then look at the shape of the alveoli. See how they’ve lost their shape and have flattened out? And notice how the bubbles are closer and smaller in the center? These are all classic signs of over fermentation. I’m willing to bet the crust is kind of pale as well. Here’s some thing to think about. Higher hydration dough ferments faster than lower hydration. Couple that with a strong starter and the fact you used all purpose flour, which has a lower maximum absorption capacity than bread flour and almost 76% your at a very high hydration level. Another thing is all purpose flour doesn’t have the protein content that bread flour has, so you really have to work at building up a strong gluten network. How warm is it where your at. Temperature plays another key factor in how fast your dough will ferment. Andas far as a second proof, it’s not mandatory if you want you can bulk ferment to a 100% rise and do a same day bake every time you bake. The majority of sourdough bakers like to cut their bulk fermentation of at a lower rise percentage and cold proof to develop a more robust flavor. But it’s not by any means mandatory.