What am I doing wrong? Very dense crumb with minimal bubbles.

I’ve been using @amybakesbread recipe on Instagram which is Levain: 90g active starter 90g room temp water 90g white bread flour Dough: 230g levain 400g room temp water, about 70ish 600g white bread flour 12g salt 3 stretch and folds 1 hour apart, and I’ve been leaving it on the counter for an hour after that. It doesn’t rise much on the counter though. Then bulk ferment for 24-48 hours. Preheat oven to 500, drop down to 450 and bake for 25 mins in a Dutch oven with lid on, then 20 mins with lid off. Let cool completely for