The P2SH feature currently in use was introduced to Bitcoin in 2012 with BIP-0016. It was successfully activated on 2012-04-01 with block 173805.
The BIP turned a particular "hashlock" locking script pattern (
OP_HASH160 OP_DATA_20 20-byte-value OP_EQUAL) into a "magical" bytecode pattern which, after authenticating an input's top stack element against the hash then also executes it using Script VM.
The BIP references 1 historical transaction that spent from an output that matched the pattern:
These new rules should only be applied when validating transactions in blocks with timestamps >= 1333238400 (Apr 1 2012) . There are transactions earlier than 1333238400 in the block chain that fail these new validation rules. . Older transactions must be validated under the old rules. (see the Backwards Compatibility section for details).
which made me wonder - are there other, unspent, historical hashlock outputs which may have been made unspendable (if they weren't already) by introduction of the P2SH feature?