While some protocols require value attached to OP_RETURN outputs, this otherwise seems like a mistake.

Setting the value to 0 should really be done by the wallet/script creating the transaction (like createrawtransaction does for `data` outputs). However, as an additional check, similar to the high-fee check, sendrawtransaction could also check for non-zero value OP_RETURN outputs.

This should be configurable by a new RPC argument.

See also https://transactionfee.info/charts/output-opreturn-amount/

#### Useful skills:

* Bitcoin Core RPC code
* Transaction output types
* Bitcoin Core functional tests

#### Want to work on this issue?

For guidance on contributing, please read [CONTRIBUTING.md](https://github.com/bitcoin/bitcoin/blob/master/CONTRIBUTING.md) before opening your pull request.

#include <rpc/blockchain.h>
#include <kernel/mempool_persist.h>
#include <chainparams.h>
#include <core_io.h>
#include <fs.h>
#include <kernel/mempool_entry.h>
#include <node/mempool_persist_args.h>
#include <policy/rbf.h>
#include <policy/settings.h>
#include <primitives/transaction.h>
#include <rpc/server.h>
#include <rpc/server_util.h>
#include <rpc/util.h>
#include <txmempool.h>
#include <univalue.h>
#include <util/moneystr.h>
#include <util/time.h>
#include <utility>
using kernel::DumpMempool;
using node::DEFAULT_MAX_RAW_TX_FEE_RATE;
using node::MempoolPath;
using node::NodeContext;
static RPCHelpMan sendrawtransaction()