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.
set<CBlockIndex*, CBlockIndexWorkComparator> setBlockIndexCandidates;
    /** All pairs A->B, where A (or one of its ancestors) misses transactions, but B has transactions.
     * Pruned nodes may have entries where B is missing data.
     */
    multimap<CBlockIndex*, CBlockIndex*> mapBlocksUnlinked;
    CCriticalSection cs_LastBlockFile;
    std::vector<CBlockFileInfo> vinfoBlockFile;
    int nLastBlockFile = 0;
    /** Global flag to indicate we should check to see if there are
     *  block/undo files that should be deleted.  Set on startup
     *  or if we allocate more file space when we're in prune mode
     */
    bool fCheckForPruning = false;
    /**
     * Every received block is assigned a unique and increasing identifier, so we
     * know which one to give priority in case of a fork.
     */
    CCriticalSection cs_nBlockSequenceId;
    
    int32_t nBlockSequenceId = 1;
    
    int32_t nBlockReverseSequenceId = -1;
    
    arith_uint256 nLastPreciousChainwork = 0;
    
    set<CBlockIndex*> setDirtyBlockIndex;
    
    set<int> setDirtyFileInfo;
} 
CBlockIndex* FindForkInGlobalIndex(const CChain& chain, const CBlockLocator& locator)