Google is said to be testing a carousel design that can hold up to 12 pages. But users could only see up to five at a time instead of eight. As a result, users must scroll and tap rather than tapping it; this would end up the section as no longer which benefits the “discover and following/RSS feed” only marginally.
This change stems from redesigned Chrome that attempted to have completely overhauled the New Tab Page.
Aside from the carousel for recently visited sites, another carousel for "Continue browsing" is expected wherein users open tabs and replace the Tab Grid. That design was never widely adopted, but it was notable for challenging Chrome's navigation paradigm and elevating the NTP above the tab switcher.
It has been observed that Google has toned down that design in recent months, but the carousel is reappearing. It's not a major change, but it adds unnecessary horizontal scrolling and slows down interaction with the New Tab Page.
This carousel on the New Tab Page isn't available to all users yet, but it started appearing on more of my devices over the weekend.