Bulk Fermentation Differences

I have been testing with Foodgeek's Master Sourdough bread recipe. I follow it to the tee but in the past the BF to 25% has always led to my loaf being super underfermented. It comes out fine between 75-100% rise for me. Just wondering what the explanation could be here if all other parameters are the same? My starter has no problems doubling in size within 3-6 hours.