The new skin picker's list of skin packs displays fewer packs the farther you scroll down. After scrolling down an estimated 250 packs, the bottommost part of the list is no longer filled. The farther you go, the smaller the filled fraction becomes. Eventually only one skin pack is displayed. I stopped trying to find the limit at that point.

I have had similar problems with very long scrolled lists in programs I've developed. They were caused by accumulated rounding errors in calculating the scroll bar position.

Attached screenshots show the progression.

Steps to reproduce:

1. While connected to the Marketplace content, open the skin picker.
2. Scroll the list of skin packs down repeatedly, past several hundred skin packs.

Actual results:
Only a fraction of the skin pack list is populated, even though you are not at the end of the list. The size of the populated fraction decreases the farther you scroll down.