I’m having the same issue with my pool built in July. It developed a ridge in the hopper wall in the deep end. And then another depression formed right in the slope from the shallow down to the deep end. I spoke to the builder who sent someone out to check out the first ridge and said “that’s weird.” They said before closing they will pull the liner back and fix it, then reinstall the liner. After the second depression formed in the shallow end I spoke to another PB who I wish I hired to do the original install. He told me it’s not normal but said it happens from time to time if the vermiculite was too thin and/or there was settling.
With regard to the depression he said the PB could have overdug or pulled out a root or something in that spot and backfilled with dirt instead of gravel, leading to settling underneath. My PB is coming out in early October to fix the problems, before closing. The thing that worries me the most is they’ll have to pull back most of the liner and then get it back in place. They’ll have to remove it from at least the bottom drains but I’m hoping they can keep it attached at the skimmers so they don’t have to try and hit the same screw holes when putting it back on.