Airports and flight data feeds don't publish the reason for a delay. Only the airline knows: check its app, email or text messages, or ask at the gate, and keep a screenshot. The reason decides whether you're owed compensation:
Usually owed: technical problems, crew shortages, the airline's own staff on strike, a late incoming plane.
Usually not owed: bad weather, air traffic control restrictions or strikes, security risks, airport staff strikes.
Always: free meals and drinks during long waits, and a hotel if you're stuck overnight, whatever the reason.