What common mistake do developers make with Indexes, why does the mistake cause problems, and what is the safer approach?

What common mistake do developers make with Indexes, why does the mistake cause problems, and what is the safer approach? One recurring problem with indexes is applying it without understanding the boundary it protects. Changing production schema manually and leaving the migration history out of sync with the real database. In addition, Migrations can define indexes that support important lookup and ordering patterns. Safer engineering approach: keep the responsibility in the correct layer, use the framework's supported API, validate and authorize inputs, avoid hidden side effects, and verify the behavior with tests.