Also as posted here:
While our goal was to provide viewers a way to easily support streamers by purchasing games and in-game items directly from Twitch, we found that this feature as implemented did not provide most streamers with significant additional revenue. We are discontinuing this feature to invest in other ways to help viewers obtain games and in-game items directly on Twitch while supporting streamers – including through Extensions 6 on Twitch like Amazon Blacksmith 10, which allows viewers to support streamers through purchases of games and other item
Most of it is moving to Blacksmith