Bitcoin Script just got more expressive: A transaction including an OP_CAT Script has been included in block 856182

Transaction: 51bae58fa9d413b86d74da60d5366987dcdeb0586d39b93b2ca22f9e40dc83de.

Block: 856182

OP_CAT is one of the many proposals that are trying to make their way into Bitcoin Core, although not exclusively a covenant proposal, but a way to concatenate elements from the Stack on a Script, OP_CAT could emulate the behaviour of many other

Covenants, which are no more that specific spending conditions, allow for many improvements to the Lightning Network, cordinatorless coinjoins, BitVM, L2 bridges and many other things that can't be properly done today in Bitcoin due to Script's lack of expressivity.

OP_CAT transactions, although non-standard are valid, since nodes not enforcing OP_CAT only need to read it as OP_SUCCES. The only way to get OP_CAT out of Bitcoin would be by reorging the chain or hard forking.