The same 24 months of purchases. A snapshot model (RFM) files him as low value for almost the whole stretch. A model that reads the sequence (HMM) sees him change state at month 14. The snapshot only catches up at month 18. Drag the timeline and watch the two readings disagree.
HMM flagged the turn at month 14, the moment 847 made one purchase outside his usual pattern. RFM kept calling him low value until month 18, after the new rhythm had stacked up in its rolling window. Four months of treating a customer as what he was, while he was busy becoming something else.