The image you included is not that of a search -- that is a category that you are browsing; searches must use keywords. eBay treats searches differently than just category browsing. You cannot save a category, though you can still bookmark the page.
Try searching that category using a very broad set of keywords:
https://www.ebay.com/sch/i.html?_from=R40&_nkw=%280%2C1%2C2%2C3%2C4%2C5%2C6%2C7%2C8%2C9%2Cquarter%2C...
Then you should be able to save the search. That search should match any result in that category that contains any number or any of those words in the title or description, which should be most all of them.
If you still cannot save a search:
How many saved searches do you have saved? Close to the maximum of one hundred? The easiest way to check the number is to open your feed page:
https://www.ebay.com/feed
The number of saved searches and saved sellers should be near the top of the page.
If you sign out of your account and search, do you see the link then?
Does the link reappear if you delete a search? Try bookmarking the search just in case you cannot save it again.
Do you see the button if you use the eBay app on your phone?
I still see the "Save this search" link and heart icon at the top of my search results, so it does not appear that eBay has removed it. Sometimes eBay will try a limited experiment that only affects a few accounts to test something.
