Sounds like it might be the "oil canning" pop sound from the metal plate over the battery pack. That's a known sound on the Model 3 and I suppose would happen on the Y as well. What's basically happening is that there is a large metal plate. It has a bit of tension as temperature changes, and the metal is trying to expand or contract. If there is some air pressure difference between the two sides, it can be pressing on the sheet, and at some point, it can make a "pop" noise as the curvature of the plate flexes into the other direction. So it's the same kind of effect if you have a metal oil or gas can that is sealed, and your garage heats up or cools down, and the bottom of the metal can pops from the air pressure changes of inside versus outside.
Owners frequently have observed it during Supercharging, because that's heating up the battery pack. There is a service bulletin related to this, where they change something with the "breather valves" that let the air pressure equalize between the inside and outside, so it doesn't have to let that pressure build up.