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Lookup sync has a cache of block roots "failed_chains". If a peer triggers a lookup for a block or descendant of a root in failed_chains the lookup is dropped and the peer penalized. However blocks are inserted into failed_chains for a single reason: - If a chain is longer than 32 blocks the lookup is dropped to prevent OOM risks. However the peer is not at fault, since discovering an unknown chain longer than 32 blocks is not malicious. We just drop the lookup to sync the blocks from range forward sync. This discrepancy is probably an oversight when changing old code. Before we used to add blocks that failed too many times to process to that cache. However, we don't do that anymore. Adding a block that fails too many times to process is an optimization to save resources in rare cases where peers keep sending us invalid blocks. In case that happens, today we keep trying to process the block, downscoring the peers and eventually disconnecting them. _IF_ we found that optimization to be necessary we should merge this PR (_Stricter match of BlockError in lookup sync_) first. IMO we are fine without the failed_chains cache and the ignored_chains cache will be obsolete with [tree sync](https://github.com/sigp/lighthouse/issues/7678) as the OOM risk of long lookup chains does not exist anymore. Closes https://github.com/sigp/lighthouse/issues/7577 Rename `failed_chains` for `ignored_chains` and don't penalize peers that trigger lookups for those blocks Co-Authored-By: dapplion <35266934+dapplion@users.noreply.github.com>