Did it say it needs to be replaced or needs to be tested to see if it must be replaced?
I went through this operation with Enedis myself. It seems that it depends upon which company manufactured the breaker.
I had to take photos of my two Linky boxes and answer questions and then submit online. I have not received a response so assume mine are not a danger to life.
You have received a letter that has been distributed for quite some months. A bad, or perceived to be bad, bunch of main disjoncteurs have been supplied from the manufacturers and need attention. LL the letters that I have seen, and that is in excess of twenty, have only suggested that the switch may be faulty, not are definitively faulty. In all cases a call to the number on the letter will allow you to identify the switch and if it is a suspect model arrangements will be made to replace it at no cost.