Why does my loaf not have a more open crumb?

https://preview.redd.it/wdgnu8oo82ag1.jpg?width=3024&format=pjpg&auto=webp&s=e1929e98f102e23f92a98f9c63711fe5d67ab112

https://preview.redd.it/kwppzt9p82ag1.jpg?width=3024&format=pjpg&auto=webp&s=c2660414b5ed862dbf394dc5078f10fea1a3e7dc

I got a great rise in the oven on this loaf, but when I cut into it, there were very few holes. I've been baking sourdough for a while and haven't had this problem until recently. Does anyone know why?!

Recipe:

500g bread flour
350g water
100g starter
8g Himalayan sea salt
20g white miso paste
7g sesame oil
30g sesame seeds

Process:

Mix all ingredients (minus the sesame seeds) together and let rest 1hr
Four sets of stretch and folds, add the seeds in the third stretch
BF for about 6hrs in a relatively cold apartment
Cold proof for 10hrs in fridge
Bake in a preheated bread oven at 450°F for 28min covered, 18min uncovered
Cooled for about three hours before cutting

Thanks for the help!