Someone grew up in a Protestant faith.
They then want to convert to Catholicism.
They do not get a conditional baptism because they think they were validly baptized already and they have documentation that a baptism has been performed in their Protestant community.
They then convert to Catholicism and get Confirmed and receive First Communion.
They live the rest of their life following Christ and His Church.
What if their baptism in the Protestant faith was not valid (i.e. the Protestant minister forgot to say "I baptize you in the name of the Father and of the Son and of the Holy Spirit") and they never find out that their baptism wasn't valid?
What would happen to this person? Would baptism of desire cover them?