The easiest way to lose a team is to change the rules halfway through the game.

People can handle hard rules. What they cannot handle is rules that move, because then effort stops being connected to outcome and there is nothing to aim at. Once that link breaks, everyone switches to guessing what you want today, which is exhausting and produces nothing. Consistency is not about being rigid, it is about being predictable enough that people can plan.

If something genuinely has to change, say that it is changing, say why, and say when it starts. That one extra sentence is the difference between a decision and a betrayal. Then hold the new version long enough for anyone to work under it.