I've seen this in my Dexa scans.The reason for this is that large weight on your bone structure (like from squats and deadlifts) causes increased activity of osteoblasts within the bones. So in addition to the increased strain on skeletal muscle and hypertrophy, will also actually increase bone thickness and density as well. I'm like you, @maldorf where even though my ideal weight is 168 lbs, I could NEVER reach. Maybe 180 or 190 but never in the 160's. I'd be nothing but bones and skin.
In 2016 my bone mineral content was 7.9lbs; in 2021 with 34lbs. more lean tissue it's 8.7lbs.
In 2016 my bone density was 1.402; in 2021 it was 1.516. My bone density is now 3 standard deviations above normal.