It is surprisingly common for Steam to auto-update you past this version. To ensure you are on this specific, stable build:
: This specific update (v1.2.11) is centered on a deep technical overhaul of the multiplayer infrastructure. It improves backend scalability, reducing connectivity issues during high-traffic events, such as the 500-player Siege tests. Mount and Blade II Bannerlord v1.2.11.45697
For the multiplayer community, patches are life or death. brought subtle but important changes to the multiplayer spawn system. It is surprisingly common for Steam to auto-update