It says gallon. I'm guessing that's a four quart package for a total of one gallon.
I've seen this kind of tricky thing on the interweb.
Show a picture but states the quantity in the text so we can't say false advertising.
Unless you have bought 4 gallons for that price to verify it.
OT maybe, but I prefer Lowe's for several reasons.
Top of the list is Lowe's is pet friendly. My Home Depot has a no pets sign.
And the last time I returned a quart of paint at Home Depot, the girl opened it to see if I was a crook.
Sort of insulting since I had pulled a not full can of that very primer off the shelf previously and handed it to the check out person to alert them to it.
The next time I bought the primer I found that can back on the shelf.
I bought some of the primer at Lowe's last week.