Don't know Vasque, but I hunt in my Nick's, or my White's for the past 2 decades.
Typically when they "squeek" they are dry, and are squeeking between the leather and the rubber in the heel/sole area.
Obenauf's boot oil/grease is what I use. If you go and buy Nick's or White's Branded oil, THAT is what it is.... Just at the premium of the name.
About once a year mine REALLY need a good working over(work, play, fightfireing). Clean them up, and dry them out. Then REALLY get a good application, I usually do two coats. Then ALSO to the inside of them.
Squeek solved.