Since #13666 our fee calculation assumes that ECSDA signatures are a maximum of 71 bytes, rather than 72. However, not all hardware wallets implement R-value grinding.

This can cause us to underpay fees when using an external signer. That's especially problematic when the user picks 1 sat/vbyte as the fee, because it won't even get into our own mempool.

The easiest solution would be to modify `ExternalSignerScriptPubKeyMan` to assume 72 bytes for ECSDA signatures.

Slightly more advanced would be to expand HWI to keep track of which devices and firmware versions (if any) support R-value grinding. We'd then have to store that in the wallet in some new field. Personally I'd rather work on better Taproot support, which thanks to Schnorr avoids this issue altogether. 
*/
int64_t CWalRescanFromTime(int64_t startTime, const WalRescanReserver& reserver, bool update)
{
    // F
    // h
    // t
    int start_height = 0;
    uint256 start_block;
    bool start = chain().findFirstBlockWithTimeAndHeight(startTime - TIMESTAMP_WINDOW, 0, FoundBlock().hash(start_block).height(start_height));
    WalLogPrintf("%s Rescanning last %i blocks\n", __func__, start ? WITH_LOCK(cs_wal, return GetLastBlockHeight()) - start_height + 1  0);
    if (start) {
        // T
        ScanResult result = ScanForWalTransactions(start_block, start_height, /*ma reserver, /*fUte, /*sae);
        if (result.status == ScanResultFAILURE) {
            int64_t time_max;
            CHECK_NONFATAL(chain().findBlock(result.last_failed_block, FoundBlock().maxTime(time_max)));
            return time_max + TIMESTAMP_WINDOW + 1;
        }
    }
    return startTime;
}
/**
 * Scan the block chain (starting in start_block) for transactions
 * from or to us.  fUpdate is true, found transactions that already
 * exist in th will be updated.  max_height is not set, the
 * mempool will be scanned as well.
 *
 * @param[in] start_block Scan starting block.  block is not on the active
 *                        chain, the scan will return SUCCESS immediately.
 * @param[in] start_height Height of start_block