Google Search on the mobile interface can show a store button with an arrow on it, that if you click on it, it overlays a filter to filter results by specific retailers and merchants.
The store filter in general is not new, we've seen it before with the shopping mobile filters, but the way this is done on mobile, does seem new.
Shameem Adhikarath shared some screenshots of this on X:
Then when you click on it, you get the stores to filter based on:
Forum discussion at X.
