A more detailed example: Let's say I find a game using itch.io's search filters; let's call it "Copper".
If I type "Copper" into the desktop app's search bar (above the tabs), Copper would not show up.
However, if I open Copper's page in the app (using the search filters), the search bar above the tabs would then start working correctly and searching "Copper" would display the correct result from now on.
But that would still not match the website's search, the website would show much more than just that one result.