After upgrading to Django 5.1 I am seeing this warning:

  /python/lib/python3.11/site-packages/rest_framework/urlpatterns.py:108: RemovedInDjango60Warning: Converter 'drf_format_suffix' is already registered. Support for overriding registered converters is deprecated and will be removed in Django 6.0.
    register_converter(suffix_converter, converter_name)

Relevant discussion on Django issue tracker: https://code.djangoproject.com/ticket/35090

Digging into it a little further, it looks like DefaultRouter calls register_converter when building urls. Our project has several DefaultRouters, so this converter is registered several times, which in effect does nothing since it just replaces what's there with the same thing.

The fix could be as simple as throwing an if converter_name not in get_converters(): check above the register_converter call in rest_framework.urlpatterns.format_suffix_patterns?