Are you proposing just to add new field to a JSON response, even though they are not needed?
That is exactly what OP is proposing and it makes total sense. More data != bad. Just ignore if you don't need it. For 99.999% of cases the bandwidth of extra data is entirely negligible.
For business cases you just want to get things done. If the server has added more data, which is obviously relevant in some regard, you can see it and might want to use it etc. With GraphQL you are completely stuck without SPECIFICALLY requesting it. That means every client needs to know about the new data and specifically request it. In theory that might sound like it makes sense, but in practice this is virtually never the case.
Give me all the data and I'll use what makes sense.
(Most) GraphQL clients are optimized for relatively small/simple objects being returned, and you typically pay a cost for every single edge (not node) returned in a response / cached in memory.
It can quickly get to the point where your project is spending more time per frame processing GraphQL responses & looking data up from the cache than you spend rendering your UI
