One poster indicated opening the gallon container and pouring out a glass before resealing it to freeze ensured it didn’t explode in your freezer.
I’ve never tried freezing milk as my freezer is usually full of venison.
We’ve never had that problem with milk in normal plastic containers. Maybe they just don’t fill them all the way to the top in our part of the country. They do bulge a bit, but go back to normal when thawed out.
We have two, both filled to the max. You have to put on thermal underwear and insulated gloves when looking for something. For some reason, whatever we’re wanting is always at the very bottom - haven’t figure out why yet - but I’m working on it.