Yes, I was wrong and thinking of something else. But the rest of the analysis stands: congress need not have to formally declare war to meet constitutional mandate.
They have to authorize it for the Constitutional power they have to be observed.
The formal/legal declaration need not say “this is a declaration of war” - there is no requirements under the Constitution for any such specific language. But it is an absolute requirement.
Congress shall have the power.... to declare war.
Nobody else has that power under the Constitution.
It is an absolute.
It is a necessity.
The language it consists of is entirely optional.