Bitcoin Core merges Taproot/Schnorr/Tapscript consensus implementation
Bitcoin Core merged the consensus implementation of BIPs 340, 341 and 342, bringing Schnorr, Taproot and Tapscript code into the reference client without activating the new rules.
Pull request #19953 was merged in October after an extended review process. The code implemented validation for the Schnorr/Taproot/Tapscript proposal set so Bitcoin Core could enforce the new rules if and when the network later activated them.
The merge was deliberately separate from activation. Nodes running the code did not begin enforcing Taproot simply because the implementation was present; activation parameters still required a separate consensus and deployment process.
That separation is historically important. It shows Bitcoin's conservative upgrade process in practice: specification, implementation, code review, release and activation were distinct stages, with the 2020 merge preparing the software foundation for the 2021 soft fork.