`RewindBlockIndex` reads `chainActive` (via `ChainActive()`) without holding `cs_main`:

https://github.com/bitcoin/bitcoin/blob/b2a6b0216192b6e8428f1a80b47f5178fccb961a/src/validation.cpp#L4314-L4331

(Please note that callers of `RewindBlockIndex` are _not_ allowed to hold `cs_main` since `RewindBlockIndex` indirectly calls `LimitValidationInterfaceQueue`.)
{
    if (!tx.IsCoinBase())
    {
        if (pvChecks)
            pvChecks->reserve(tx.vin.size());
        
        
        
        
        
        
        
        
        if (fScriptChecks) {