Subclasses of IOSSystemContextMenu have custom toString methods, e.g.:

In cases like these, we should instead prefer Diagnosticable and debugFillProperties. This integrates with devtools and provides structured, consistent output.

See the styleguide: https://github.com/flutter/flutter/blob/master/docs/contributing/Style-guide-for-Flutter-repo.md#override-tostring

This came up in #169150 (comment).