Renamed to skit-ai/elm-flow-chart. That is where the repository lives now. It has not been published as a package under the new name.
Versions published as vernacular-ai/elm-flow-chart still install under that name. 4 versions of 4 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/skit-ai/elm-flow-chart.
What we checked: The repo moved to github.com/skit-ai/elm-flow-chart and tag 2.1.0 is there; its commit 1e6c9e35153c is from 2019-05-22 14:01 UTC, before the version was published (2019-05-22 14:03 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/vernacular-ai/elm-flow-chart/zipball/2.1.0/
Encoders and decoders for flowchart data types
encoder for a FCNode
encoder for a FCPort
encoder for a FCLink
vector2 decoder
FCNode Decoder
FCPort Decoder
FCLink Decoder
encoder for Vector2