How the detection works, and where it stops
The tool checks the label credited on the release and the copyright line against a list of distributor names, including DistroKid, TuneCore, CD Baby, The Orchard, AWAL, ADA, Believe, Ingrooves, Symphonic, EMPIRE, UnitedMasters, ONErpm, Amuse, FUGA and the in-house arms of the three majors.
A match in the copyright line is the strong case, because that line frequently reads under exclusive license to the distributing company. A match in the label field alone is weaker: some artists name their imprint after nothing in particular, and some labels contain a major's name without that major distributing them.
When neither field carries a recognisable signature, the tool says so rather than guessing. Plenty of releases genuinely do not expose their distributor anywhere public, and a confident wrong answer would be worse than none.
Why anyone needs to know
Artists choosing a distributor want to know what the releases they admire actually use, which is more informative than a comparison table because it shows what survives contact with real catalogs.
Labels and managers need it for practical reasons: a takedown, a metadata correction or a re-delivery has to be raised with whoever controls the delivery, and if you inherited a catalog you may genuinely not know who that is.
Reading the evidence
Every answer shows the field it matched (label or copyright), the exact text it matched inside, and a confidence level. Treat medium confidence as a lead to verify, not a fact. The release UPC is shown alongside, which is what you would quote in any support ticket to a distributor.
Results come from Deezer's public catalog and Apple's public album data, so anything commercially released and distributed to streaming should be found. Unreleased tracks, private uploads and releases that never reached streaming will not appear.