What permissions are required to return rows from information_schema.schemata?
The user needs to be the owner of a schema to get any rows from information_schema.schemata

alter schema $schemaName owner to $user;


Or the user needs to be a member of a group that owns the schema

Usage grant is not sufficient. The user does not need to be a superuser. The user can own a table in a schema, but that is not sufficient either.