Figured it out (sorta). Before, I would decimate at 50% over and over until I got down to where I wanted to be and it kept its shape. Doing that now causes it to loose shape along the way until it gets really far off.
I took the slider and slid it to 1% and it decimated in one round and kept its shape like it did before.
Side note: when decimating at 50% over and over, I get patches of less-decimated areas. Almost like it’s sacrificing some areas shape to keep higher resolution in some areas. See vid: