The Rev. Andres Arango of the Diocese of Phoenix was baptizing people by saying “We baptize you in the name of the Father, and of the Son, and of the Holy Spirit.” Instead, he should’ve been starting with “I baptize you”.
“The issue with using ‘We’ is that it is not the community that baptizes a person, rather, it is Christ, and Christ alone, who presides at all of the sacraments, and so it is Christ Jesus who baptizes,” Bishop Thomas Olmsted wrote in a January announcement.
If it is Christ and Christ alone who baptizes, then "I" is just as incorrect as "We," because saying "I" is saying that it is the officiant who is doing the baptism. But, since the language says "... in the name of Father and of the Son and of the Holy Spirit," then I don't see how it makes any difference
who is doing it "in the name of" the aforementioned Holy Trinity.
I have always thought of baptism ceremonies as being communal. Not in that it is the community that baptizes, but that the community bears witness to the baptism. And I think that's valid regardless of whether the officiant says "I" or "We."
Beyond that, in the Roman Catholic Church the order of the seven sacraments ( baptism, confirmation, the Eucharist, penance, holy orders, matrimony, and anointing of the sick) is important. Technically, if any of those whose baptisms have been ruled invalid thought they were married in the church -- their marriages are now also invalid.