While it is true to say that a Mass cannot be either valid or invalid, instead an individual act is valid or invalid…
The practical consequences are that if there is no valid consecration of the Eucharist, then there is no Mass. It would be an invalid attempt at Mass.
We speak the same way about marriages. The accurate phrasing is “invalid attempt at marriage” rather than “invalid marriage.” Nevertheless, as a sort of shorthand way of speaking, we sometimes just say “invalid marriage.”
An invalid attempt at Mass is not an “invalid Mass” because that phrase makes no sense—an invalid act cannot be a Mass, and conversely, if there is a true Mass it is always valid.
In casual speaking, if one says “an invalid Mass” as a substitute for “an invalid attempt at Mass” such a grammatical error is minimal and is typically overlooked.