There are reports that the filetype operator within Google Search has stopped working, it has not. It doesn’t work when you add additional search operators to it, like a site command to see a specific file type on a specific type. Google has said it is likely a bug and they are working on bringing it back.
If you search for PDF files on this specific site using the command [site:seroundtable.com filetype:pdf] you currently get zero results:
But in general, if you are trying to find PDF files or other filetypes for a specific query, that still works just fine. For example; [google quality raters guidelines filetype:pdf]:
Update: It might be fixed, it works for [site:cnn.com filetype:pdf]:
Danny Sullivan, the Google Search Liaison, said on X, “This is probably a bug. I’m passing it on to our team to investigate.”
This is probably a bug. I’m passing it on to our team to investigate.