@defer/@stream are experimentally supported by Apollo Server V4.

But the June 2023 spec is not yet supported.

Ideally, the server could respond in either format based on the value of deferSpec provided by the client: deferSpec=20220824 or deferSpec=20230821, which was set up nicely to support such a situation.

A switchable response format would allow both Apollo and urql clients to use incremental delivery, as urql has upgraded to the new spec.