Looks like this project is archived.

Normally, owners archive projects when they are no longer interested in maintaining them.

Why Typedescriptor checks for it

Typedescriptor doesn’t list dead projects unless they are particularly vital to the .NET ecosystem or are the transitive dependencies of other listed projects. Archived projects are a very good sign that the project is dead.

How to fix this problem

Reach out to a moderator if the project is an important .NET project. If not, then investigate whether the project can be unarchived or forked and re-released.