Can you please provide some examples of the search query you're using, and the resulting Spotify search results? An output of your browser HTTP requests would also be really helpful to confirm the actual HTTP requests sent to the Spotify API.

For example:

Ok for example, searching for the track "Infinity" from the artists "Sefa" and "D-Block & S-te-Fan" (query being sefa infinity).

The Spotify client has the track I want as the very first result.
On Iris it is the... (/me counts) 27th result.

Following screenshots are in order from top to bottom (I had to scroll the page quite a bit):

Browser requests for that query:

So I'm looking into the response to the actual Spotify request. The result in Iris makes no sense to me compared to what Spotify gives me. The right search result is present as the very first item in the list of albums, artists and tracks. I'm assuming the album, artist and playlist results are used for the segments at the top of the page so I'm ignoring that.

If the right track is the very first result in the list of tracks, why does Iris then show it way down in the list?

The issue isn't so much that results are inaccurate, rather the order is not the same as in the Spotify client. That the Spotify API returns results the same as the Spotify Client is helpful.

The solution here (as I see it; open to other suggestions!) is to add a new sorting option for search results: "As loaded". This is the same as in other views (Library -> Playlists for instance) and does not apply any sorting of results, meaning that they're displayed however they are returned from their respective sources.

Note that this will mean results are bundled together (ie all Spotify results and then Local results) but the order of each bundle will be unpredictable.

Starting from Iris version 3.67.0 spotify search results are totally different than for previous versions and my wife is very dissapointed with that :( so I kindly ask if we can go back to previous search algorithm, cause I need to stay on version 3.66.1 if I want to get laid :-D

The issue isn't so much that results are inaccurate, rather the order is not the same as in the Spotify client.

Actually, to the end user this is "inaccurate". You just get completely unrelated results first. It's fine if those were way down the list, but they're not. Instead they're represented as "the best match for your query" which they're (obviously) not by a long shot.
"As loaded" as an additional option would be nice but honestly, this ordering shouldn't even be a thing in the first place.

What exactly is the current ordering? Does it for some reason show the results ordered exactly the opposite of what one would expect? Does it somehow smash together multiple sources inaccurately? I just don't know what I'm looking at 🤔

EDIT: actually I figured it out, the ordering is alphabetical. That makes in my opinion no sense for search results...