In v2 change streams in ignore-removed-shards mode, the change stream shard targeter has a startChangeStreamSegment method, which can be called multiple times during the lifetime of the change stream.
This method is responsible for opening the cursors to the set of shards that cover the segment.
If this set contains the config server, the startChangeStreamSegment method will unconditionally open the cursor to the config server, even if such cursor is already open on the same change stream.
This is wasteful, because it will build the full pipeline for the config server cursor and will actually open the cursor!