Duct. Duck is a brand name

Yes. But also mostly no.

Wikipedia:

“Duck tape” is recorded in the Oxford English Dictionary as having been in use since 1899 and “duct tape” (described as “perhaps an alteration of earlier duck tape”) since 1965

and:

In 1971, Jack Kahl bought the Anderson firm and renamed it Manco. In 1975, Kahl rebranded the duct tape made by his company. Because the previously used generic term “duck tape” had fallen out of use, he was able to trademark the brand “Duck Tape” and market his product complete with a yellow cartoon duck logo. Manco chose the term “Duck”, the tape’s original name, as “a play on the fact that people often refer to duct tape as ‘duck tape’”, and as a marketing differentiation to stand out against other sellers of duct tape.

People should really do the bare minimum double-check before showing their whole ass.

As others have noted, “duct tape” is the last thing you want to use on ducts. Better to actually call it “duck tape,” as it was for the first 65 years of its existence.

Duct tape, as in the grey fiber reinforced tape that we typically think of, is not really a good solution for actually taping ducts.

When you are taping ducts, you typically want to use some type of foil thing, like this, but there are many varieties.

Of course, tape for ducts is, kinda, duct tape by definition. As you can see by how it’s categorized on the home despot site.

The popular form of duct tape doesn’t have similar rates of expansion/contraction to ductwork making it a bad choice for ducts.

Not as bad as op’s tortilla choice, though.

Akshully, the tape was originally called “duck tape” because it was made from a fabric called “cotton duck canvas”

It’s named after the fabric, cotton duck.

Here in Europe the choice is pretty limited.

The fact that it’s overpriced doesn’t mean that it’s good.