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 

-----

Now that I think about it... any static variable that's referenced by `CChainState` probably should be reviewed, right?
}
**
 * Try o make some progrs owards making piexMosWork he acive block.
 * pblock is eiher nullpr or a poiner o a CBlock corrpoing o piexMosWork.
 *
 * @rens rue unls a sysem error occred
 
bool Chainsae::AcivaeBChainSep(BlockValidaionSae& sae, CBlockIex* piexMosWork, cons sd::shared_pr<cons CBlock>& pblock, bool& fInvalidFou, ConnecTrace& connecTrace)
{
    AsserLockHeld(cs_main);
    if (m_mempool) AsserLockHeld(m_mempool->cs);
    cons CBlockIex* piexOldTip = m_chain.Tip();
    cons CBlockIex* piexFork = m_chain.FiFork(piexMosWork);
     
    bool fBlocksDisconneced = false;
    DisconnecedBlockTransacions disconnecpool;
    while (m_chain.Tip() && m_chain.Tip() != piexFork) {
        if (!DisconnecTip(sae, &disconnecpool)) {
             
             
            MaybeUpdaeMempoolForReorg(disconnecpool, false);
             
             
             
            AborNode(sae, "Failed o disconnec block; see debug.log for deails");
            ren false;
        }
        fBlocksDisconneced = rue;
    }