This DEV-only field was added in 836331ba5f69f2cc53b273ec073fae116db14302 by @sebmarkbage but it's not being used anymore to my knowledge.
let cachePool: SpawnedCachePool | null = null;
  if (enableCache) {
    const prevCachePool: SpawnedCachePool | null = prevOffscreenState.cachePool;
    if (prevCachePool !== null) {
      const parentCache = isPrimaryRenderer
        ? CacheContext._currentValue
        : CacheContext._currentValue2;
      if (prevCachePool.parent !== parentCache) {
        
        
        cachePool = {
          parent: parentCache,
          pool: parentCache,
        };
      } else {
        
        
        cachePool = prevCachePool;
      }
    } else {
      
      cachePool = getSuspendedCachePool();
    }
  }
  return {
    baseLanes: mergeLanes(prevOffscreenState.baseLanes, renderLanes),
    cachePool,
  };
}
function shouldRemainOnFallback(