The paper introduces the concept of Markov length as a key quantity for characterizing mixed-state phases and transitions. The Markov length is defined as the length scale at which the quantum conditional mutual information (CMI) decays exponentially. The authors argue that if the Markov length remains finite during the evolution of a state under a local Lindbladian, then the state remains in the same phase. They demonstrate this by showing that there exists another quasi-local Lindbladian evolution that can reverse the original evolution. This criterion is applied to the dephased toric code state, where the Markov length is found to be finite everywhere except at the decodability transition, where it diverges. The CMI in this case is mapped to the free energy cost of point defects in the random bond Ising model, suggesting a connection between the mixed state phase transition and the decodability transition. The paper also discusses the implications of these findings for understanding mixed-state phases, including symmetry-protected topological phases, and provides a quasi-local decoding channel.The paper introduces the concept of Markov length as a key quantity for characterizing mixed-state phases and transitions. The Markov length is defined as the length scale at which the quantum conditional mutual information (CMI) decays exponentially. The authors argue that if the Markov length remains finite during the evolution of a state under a local Lindbladian, then the state remains in the same phase. They demonstrate this by showing that there exists another quasi-local Lindbladian evolution that can reverse the original evolution. This criterion is applied to the dephased toric code state, where the Markov length is found to be finite everywhere except at the decodability transition, where it diverges. The CMI in this case is mapped to the free energy cost of point defects in the random bond Ising model, suggesting a connection between the mixed state phase transition and the decodability transition. The paper also discusses the implications of these findings for understanding mixed-state phases, including symmetry-protected topological phases, and provides a quasi-local decoding channel.