Management compares velocity across teams. What do you do?

Velocity is a team-specific planning tool, not a performance metric. Story points are relative estimates that each team calibrates on its own, so one team's 40 points is not comparable to another's 40. Comparing them is meaningless and creates harmful behavior: teams inflate estimates, cut quality, or stop collaborating to look better, which is Goodhart's law in action.

What I would do:

1. Ask what management wants to know. Usually it is predictability, delivery speed or value, and those can be answered better.
2. Explain the problem with a concrete example of two teams with different estimation scales.
3. Offer better measures: cycle time and lead time, throughput, delivery against Sprint Goals, escaped defects, and customer outcomes.
4. Keep velocity inside the team for forecasting.

I would stay respectful and help management get the visibility it needs in a form that does not distort behavior.