IMO the old grid display for pages in the reader was better.

As a more active user clicking on arrows makes it more obnoxious especially for longer chapters. Being able to click one button and then see the grid of pages and going to the page you want with one click was a lot more convenient than the current UI. Updates to UI and stuff that change a fair amount should probably be announced with a message at the top of the front page. Sudden changes whose announcements are behind different pages of the site/forums are also tedious to track down. I feel like these things should be more readily made clear to the userbase, especially before they're implemented. The only benefit is that the page thumbnails are larger but it's not like the old ones were small.

The new reader you're experience is because you have beta features turned on. We state on the page https://www.fakku.net/account/beta :

All beta features are experimental and may degrade your FAKKU experience. You can turn off the beta at any time after joining.

To use the old reader, turn off your beta setting.

Thank you for your feedback.

As Kisuka mentioned, what you're currently seeing is a beta reader that's still work-in-progress.

That being said, you don't need to click the arrows to scroll the thumbs in the beta reader - the mouse wheel allows you to speed through them quite fast.

Yeah I completely forgot that I turned it on months ago when anime was being introduced to the site, and after turning it off it's back to what I'm familiar with. Thanks!