Renamed to ad-si/Vectual. That is where the repository lives now. It has not been published as a package under the new name.
Versions published as adius/vectual still install under that name. 3 versions of 7 come from the new location (see their notes).
Rerouted (renamed, verified). The GitHub user or repository was renamed. The tag is still there, at the new name. The Lamdera package server serves a copy recovered from https://github.com/ad-si/Vectual.
What we checked: The repo moved to github.com/ad-si/Vectual and tag 4.0.0 is there; its commit 0d3f2db59855 is from 2021-02-13 17:06 UTC, before the version was published (2021-02-13 17:07 UTC); elm.json is byte-identical to package.elm-lang.org's; the exposed modules match docs.json; the zip's SHA-1 is not the published one (GitHub's zip no longer comes out byte for byte the same), so the contents were checked instead.
The Lamdera compiler uses this copy and prints a one-line notice saying so. elm itself fails to download this version.
Details · package.elm-lang.org's zip: https://github.com/adius/vectual/zipball/4.0.0/
Extra types for sharing between Internal and External interface.
Alternate signature for Create.dateFromFieldsRecord
See Core.inToMonth for converting an integer month to a Month.
Alternate signature for Create.timeFromFields