Why @tag directive not generated in import array in schema

[stiew001]

Assign tag to fields which needed to be used for contracts.
[Tag("beta")] public string Country { get; set; }

Generate schema from code
var schema = await builder.Services .AddGraphQLServer() .UseField<FieldValidationMiddleware>() .ModifyRequestOptions(opt => opt.IncludeExceptionDetails = builder.Environment.IsDevelopment()) .AddApolloFederation() .AddQueryType<Query>() .AddMutationType<Mutation>() .AllowIntrospection(builder.Configuration.GetValue<bool>("AllowGraphQLIntrospection")) .BuildSchemaAsync();

In schema.graphql, the import array without @tag
schema @link(url: "https:\/\/specs.apollo.dev\/federation\/v2.5", import: [ "@key", "FieldSet", "@shareable" ]) { query: Query mutation: Mutation }

which supposed to be
schema @link(url: "https:\/\/specs.apollo.dev\/federation\/v2.5", import: [ "@key", "FieldSet", "@shareable", "@tag" ]) { query: Query mutation: Mutation }

Any idea?
I need the tag in import array for my Apollo contract filter configuration to work.