It's never been great but now seems to be completely broken. Searching for a common term lists the predicted large count of results. However only two pages of posts are displayed, & page two is the same as page one.
Here I've searched for "boost" with 692 results found but only the same page displayed twice.
I've never been able to get the "search by author" function to work.
Search page numbers seem to work fine. Initially it only shows two pages but clicking on the 2 brings up a new page and the number in the pages found changes to 1,2,3 then clicking on 3 brings up new page and the number changes to 1,2,3,4 and so on. Not great but it does increase.
As regards your other comment about search by author it appears to work ok but again not great.
Have you tried it today? What you describe is no longer working for me.
Edit: Just tried another browser & it's working as usual, so looks like a Firefox issue. Cleared cookies & back to normal. Schoolboy error! 🙄