I've been trying my hand at sourdough bread for a few months now and it is getting better and better, but this keeps happening, and I have no idea what might be the cause:
My impression is that during the rise, the crumb tears into two pieces in the middle.
This is probably relevant: The dough is 80% hydration white bread flour, around 3 hours autolysis, then lamination and three stretches and folds spaced out. Altogether around six hours of bulk fermentation, overnight in the fridge (5 °C), and baked in the morning on a pizza stone, with 250 °C with steam for 20 minutes and 220 °C for 20 minutes (the oven has the air convection turned on).
My problem is I have no idea which part of the recipe is to blame for the outcome, so I'm not even sure where I am deviating from the recipe I'm trying to copy (to be very exact, I'm trying to follow this one now: How To Make A Basic Open Crumb Sourdough Bread)
I'm not sure if this is important, but it also doesn't open up so well (but I don't have a proper lame, so I'm struggling with the scoring):