BIP 113, found in BIP-113, addressed a subtle exploit: miners can tweak block timestamps slightly. By basing locktime on the median of the last 11 blocks (MTP) rather than each block’s own declared timestamp, the network gains a more reliable measure of actual chain progression.

This ensures that transactions specifying a locktime based on seconds aren’t prematurely validated if miners set an artificially advanced timestamp. It’s another example of how Bitcoin’s consensus rules adapt to prevent even small ways to game the system. For transaction issuers, using MTP results in more predictable locktime behavior.