I know the Humble Store has a "top discounts" sort order. Beyond that, I can't say what people might be thinking of.
I can confidently say that people have been occasionally complaining about the lack of both sorting by price and sorting by discount for as long as I've been here; the complaints just seem to have gotten more heated since the redesign, since GOG actually did remove some functionality from the catalogue search, and people who don't really use that more than a couple times a year (some of whom do seem to be under the influence of faulty memories ;) ) assumed that these features were among those removed, rather than never having been implemented.

It's still anecdotal, but there are uncompleted wishes for one or the other -- or both -- of these sorting options, with comments dating back to at least 2013. (I did actually visit the Internet Archive's Wayback Machine a couple days ago to try to provide some more incontrovertible proof, but the couple archived versions of the page that I tried to load (ones from this year) just weren't loading or functioning like the "real" page, so I couldn't check the sorting options. :( )

Yeah, I'm fairly certain when I first started using GOG, it had the sort by price feature because that's how I bought my first couple of non bundle games after signing up and I remember putting it in order by price pretty clearly. It hasn't had it in years.

I also miss the discounted bundles like the D&D bundle where I picked up most of my D&D titles... I haven't seen those in ages either.

"I remember Diablo being sold here! Why did they take it away?!"

Filters are still there but after not browsing games for several months something even worse than having no filters has happened, now i can't even switch page i mean the shit is literally stuck a page 1 and clicking to next has no response hahahahahahaha no seriously GOG wtf is this shit.

Iirc that happened "now", after the last time when the gog page got new look.

And some other filters aren't working anymore.

For example, sort by oldest games doesn't work on my side.