Unlisted versions are included as upgrades.

[jawnothin]

An example would be this one:
https://www.nuget.org/packages/QuestPDF/2202.8.2

It was released incorrectly as 2202.8.2, so the author unlisted it and re-released as 2022.8.2, however now it always wants to update to this version, which is like ~100 releases behind.

[jawnothin]

Pretty sure it's the same issue as this closed issue. #75

If you change to this endpoint it will filter out unlisted versions.

https://azuresearch-ussc.nuget.org/query?q=PackageId:QuestPDF

instead of

https://api.nuget.org/v3-flatcontainer/QuestPDF/index.json

[jawnothin]

You could in theory use both, and just don't consider anything that didn't come back from the query endpoint as an upgrade, but if someone wanted to manually pick it, or already had it then it would still work. I think that's the best of both worlds without introducing a breaking change.