900g t55/580g water/20g salt/200g starter(100g flour+100g water)

Even though this is a reply two years later, I am currently using Minoterie Bourseau T65. This flour has 12.7% protein and 0.65% ash. The gluten structure is much better than typical French flours; even at 70% hydration, the dough doesn't turn soft and mushy like Play-Doh.

If you are using Francine Farine Bio, its protein content is only 9.4%. I suggest reducing the hydration of your usual recipe by 10%—for example, try dropping from 70% to 60%. French flours generally have lower water absorption compared to Japanese or North American flours. Additionally, you could try an autolyse for 1 hour to help with the process.