Why did Hamilton and co. have to wait ahead of FP3? This is the reason for a delayed start

The start of FP3 was initially scheduled for 11:30 local time. However, race control announced that the session would start five minutes later. Marshals were busy on the track with cleaning up possibly debris from the classic cars that had been racing over the circuit.

On the other hand, drivers were not too eager to get out on track. Inside the first 10 minutes of the final three practice sessions, only the two Alpine drivers and Lewis Hamilton completed laps, and the Aston Martins worked on preparing their tyres.