Don't prune finalized block

beacon_node/beacon_chain/src/migrate.rs

@@ -654,8 +654,10 @@ impl<E: EthSpec, Hot: ItemStore<E>, Cold: ItemStore<E>> BackgroundMigrator<E, Ho
             // summaries is tricky since now we keep some hot state summaries beyond
             // finalization. We will only prune blocks that still have an associated hot
             // state summary, are above prior finalization and not in the canonical chain.
-            let should_prune = if block_roots_descendant_of_finalized.contains(&block_root) {
-                // Keep unfinalized blocks descendant of finalized
+            let should_prune = if block_roots_descendant_of_finalized.contains(&block_root)
+                || block_root == new_finalized_checkpoint.root
+            {
+                // Keep unfinalized blocks descendant of finalized + finalized block itself
                 false
             } else if newly_finalized_block_roots.contains(&block_root) {
                 // Keep recently finalized blocks