[BIP Proposal] Limit ScriptPubkey Size >= 520 Bytes Consensus.

In late 2014, a significant change was implemented in the Bitcoin protocol through PR 5247 (view PR on GitHub). This change altered the STRICTENC policy behavior during the CHECKMULTISIGVERIFY process. Previously, if an invalid public key (pubkey) was encountered, the script would only fail for that specific pubkey, allowing the process to continue with the next one. However, the update introduced a stricter rule: if a pubkey with an incorrect prefix or invalid encoding is detected, the entire script fails. This modification has had tangible implications for Bitcoin users, particularly affecting those with malformed pubkeys within their Unspent Transaction Outputs (UTXOs).

A notable case mentioned recalls an individual whose funds were essentially "soft confiscated" due to this policy change. This situation arose because their UTXOs became unspendable under the new policy rules, necessitating a bypass of these rules to access their funds. The discussion suggests a call to action for those with access to extensive databases to search for bare multisig UTXOs containing strictly malformed pubkeys, highlighting the potential impact of this policy change on a wider scale. This shift from a more lenient handling of invalid pubkeys to a stringent failure mechanism underscores the evolving nature of Bitcoin's transaction verification processes and its implications for users holding assets within the network.