It seems like you must have a Symes amputation level, with that foot model?
I am not a Symes, I am a plain below knee amputee. I have never delaminated a carbon fiber foot. The last foot that I broke was a SACH foot around 1980 (prosthetist did not choose the right model for me).
I agree with punkncat, cycling does not put more stress on a foot than walking. It sounds like you are breaking feet inside the warranty period - your prosthetist needs to handle warranty exchange.