First loaf I’m really proud of!

Hello! First time poster in this sub
I’ve been making sourdough for about a month now with a starter that was gifted to me from a friend from work (starter is about 5 months old)

All of my loaves have been a success but this is the first that I am very happy with my crumb structure and overall process!

Recipe: (for one loaf but I doubled it to make 2)

• 335g warm water
• 500g bread flour
• 75g starter
• *let sit for an hour to hydrate the flour (fermentolyse)
• 12g fine salt
• mix until fully incorporated and do slap and folds or knead until a loose ball
• rest for 30 min and then begin stretch and folds
• 1 sets of 4 stretch and folds every 30 minuets
• 2 sets of 4 coil folds every 30 minutes
• after stretch and folds let proof on counter for an extra 1-2 hours (depending on temperature of dough)
• begin shaping once dough is jiggly, not sticky, and doubled in size – should pull away from side of the bowl easily
• dump dough onto lightly floured surface and shape into rectangle – fold dough into self in thirds – roll dough up – push and pull dough on bench to make it a circle
• let dough bench rest for 10 minutes then repeat shaping process to build tension
• transfer dough into banneton seam side up
• proof in banneton for 30 minutes
• cover and let cold proof in fridge for 12-24 hours
• when ready to bake preheat oven with Dutch oven inside to 250c
• Transfer loaf to bread sling on bench*
• score loaf and transfer to preheated Dutch oven
• spray top of loaf in Dutch oven with water to create steam
• bake for 30 mins with lid on
• bake for 10-15 mins with lid off
• Let cool for 2-3 hours

Please let me know if there’s anything I can improve on! And also if anyone can tell me why the bubbles at the bottom kind of form a line?
Thank you!