This fixes an issue of json/hex inputs being truncated for very long transactions. Fix [[https://github.com/bitcoin/bitcoin/pull/17618 | core#17618]]
Rationale for the value:
> The largest p2p message type is a 4 MB block? With hex encoding that should be 8 MB. Wrapped again in json, that should be less than 16 MB.
This is a backport of [[https://github.com/bitcoin/bitcoin/pull/18993 | core#18993]]