It looks like the mix
manager handles git dependencies incorrectly and when "datasource": "git-tags", "versioning": "hex"
renovate runs the hex versioning and reaches this line
https://github.com/renovatebot/renovate/blob/8b2d1fa101476880e075f57f4c28773101cefd9e/lib/modules/versioning/hex/index.ts#L104
As far as I understand mix does not support version ranges for git dependencies.
It produces an invalid newVersion from v.0.1
-> == v0.2
which fails to download the tag (because it does not exist) and mix deps.update
fails.
newVersion from v.0.1
-> v0.2