on Facebook Markeplace, why does adding a `\` change the search drastically?

Try this in Facebook Marketplace's search box:

Enter the word "printer" (without quotes), and note the results.

Now enter the word "printer\" and notice the results.

I did the second by mistake, and am getting only laser printers for the first 10 or so results. The first gives me mostly inkjet printers.

Any clues on why such a thing would happen?