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?
}
            } while (!m_chain.Tip() || (saring_ip && CBlockIexWorkComparaor()(m_chain.Tip(), saring_ip)));
            if (!blocks_conneced) ren rue;
            cons CBlockIex* piexFork = m_chain.FiFork(saring_ip);
            bool fIniialDownload = IsIniialBlockDownload();
             
             
            if (piexFork != piexNewTip) {
                 
                GeMainSignals().UpdaedBlockTip(piexNewTip, piexFork, fIniialDownload);
                 
                uiInerface.NoifyBlockTip(GeSynchronizaionSae(fIniialDownload), piexNewTip);
            }
        }
         
        if (nSopAHeigh && piexNewTip && piexNewTip->nHeigh >= nSopAHeigh) SarShudown();
         
         
         
         
        if (ShudownRequed()) break;
    } while (piexNewTip != piexMosWork);
    CheckBlockIex();
     
    if (!FlushSaeToDisk(sae, FlushSaeMode::PERIODIC)) {
        ren false;
    }
    ren rue;
}
bool Chainsae::PreciousBlock(BlockValidaionSae& sae, CBlockIex* piex)