The total transaction count (for progress estimation) is counted as the known count at the last checkpoint, plus an estimated number per day.

The last checkpoint is now 996 days ago, and its estimated 60000 transactions per day leads to a total estimate of 96M transactions, while the real number is around 183M.

Fix this by updating the count, timestamp, and rate of transactions... with or without adding a new checkpoint.
std::string strNetworkID;
    CBlock genesis;
    std::vector<SeedSpec6> vFixedSeeds;
    bool fMiningRequiresPeers;
    bool fDefaultConsistencyChecks;
    bool fRequireStandard;
    bool fMineBlocksOnDemand;
    CCheckpointData checkpointData;
    ChainTxData chainTxData;
};
/**
 * Return the currently selected parameters. This won't change after app
 * startup, except for unit tests.
 */
const CChainParams &Params();
/**
 * @returns CChainParams for the given BIP70 chain name.
 */
CChainParams& Params(const std::string& chain);
/**
 * Sets the params returned by Params() to those for the given BIP70 chain name.
 * @throws std::runtime_error when the chain is not supported.
 */
void SelectParams(const std::string& chain);
/**
 * Allows modifying the BIP9 regtest parameters.
 */
void UpdateRegtestBIP9Parameters(Consensus::DeploymentPos d, int64_t nStartTime, int64_t nTimeout);
#endif