Yep, that's why I say "(not the transactions, that's a different matter)". A block is only truly valid when its transactions are. But if there are months of blo

Yep, that's why I say "(not the transactions, that's a different matter)". A block is only truly valid when its transactions are. But if there are months of blocks after it and enough percentage of nodes are full nodes, you can safely assume it was indeed verified.