Short answer
Avoidable escalations can signal unclear authority or a need for support. Usually that’s because nobody told them they could, two departments disagree and there’s no rule for settling it, or the manager doesn’t feel ready to make the call. Agree which decisions belong at which level, set a rule for cross-department disagreements and train managers to decide. Preserve escalation routes for safety, ethics, compliance and decisions beyond the manager’s authority.
The longer answer
Track the escalations that reach you for two weeks. Sort them into three piles: no clear owner, conflict between departments and manager not confident. Each pile has a different fix.
The last step is the hardest. When a decision comes up that belongs lower, send it back with a question instead of an answer. That’s how the habit changes.