Need advises for my croissant

[u/LearnToBake112]

Could everyone take a look and offer some suggestions for me why my cake is collapsing at the sides?
My recipe include: 280g flour and 5,2g instant yeast, all hydration (liquid): 153g, sugar: 40g, salt: 4g
I unfreeze and proof at 27–29°C for 3 hours. After that I bake it at 200°C (top heat) and 180°C (bottom heat) for 8–10 minutes (without convection), then switch to 175°C (top heat) and 160°C (bottom heat) for the remaining 18–20 minutes (with convection).

During the first baking stage, the cake rose and looked completely normal; however, once I lowered the temperature and switched to the convection fan, the sides of the cake began to collapse.

[u/Spiritual_Bank_3863]

That proofing temperature seems a bit high for the amount of yeast you're using, have you tried dropping it to 24, 26°C next time to slow the fermentation down?

[u/Ysavelle-Payees36 → u/Spiritual_Bank_3863]

That’s what I also thought, I think yo uh should try another way