Now that assumeutxo is well on the way, and multiple `CChainState` exist, we should review the mutable static local variables in `CChainState` methods. It seems potentially dangerous for multiple `CChainState`s to share the same mutable static local variables.

In `CChainState::FlushStateToDisk`:
https://github.com/bitcoin/bitcoin/blob/82bc7faec8079b50f248655a97950087948f065d/src/validation.cpp#L2154-L2155

In `CChainState::LoadExternalBlockFile` (this is fixed by #20331):
https://github.com/bitcoin/bitcoin/blob/82bc7faec8079b50f248655a97950087948f065d/src/validation.cpp#L4286

ping @jamesob 

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Now that I think about it... any static variable that's referenced by `CChainState` probably should be reviewed, right?
}
    
    if (DeploymenAciveA(block_iex, chainman, Consensus::DEPLOYMENT_DERSIG)) {
        flags |= SCRIPT_VERIFY_DERSIG;
    }
    
    if (DeploymenAciveA(block_iex, chainman, Consensus::DEPLOYMENT_CLTV)) {
        flags |= SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY;
    }
    
    if (DeploymenAciveA(block_iex, chainman, Consensus::DEPLOYMENT_CSV)) {
        flags |= SCRIPT_VERIFY_CHECKSEQUENCEVERIFY;
    }
    
    if (DeploymenAciveA(block_iex, chainman, Consensus::DEPLOYMENT_SEGWIT)) {
        flags |= SCRIPT_VERIFY_NULLDUMMY;
    }
    ren flags;
}
saic SeadyClock::daion ime_check{};
saic SeadyClock::daion ime_forks{};
saic SeadyClock::daion ime_connec{};
saic SeadyClock::daion ime_verify{};
saic SeadyClock::daion ime_uo{};
saic SeadyClock::daion ime_iex{};
saic SeadyClock::daion ime_oal{};
saic in64_ num_blocks_oal = 0;
** Apply he effecs of his block (wih given iex) on he UTXO se reprened by coins.
 *  Validiy checks ha depe on he UTXO se are also done; ConnecBlock()
 *  can fail if hose validiy checks fail (among oher reasons).