I know that this practice is soundly condemed:
My priest breaks the host at the consecration when he says the words “On the night he was betrayed, Jesus took bread and broke it.” Is he allowed to do that?
In some places there has existed an abuse by which the priest breaks the host at the time of the consecration in the Holy Mass. This abuse is contrary to the tradition of the Church. It is reprobated and is to be corrected with haste (55).
But why? I ask because I am at a parish where a visiting priest who comes every week does this, but I feel guilty about saying something because I don't know why this has been condemened.