Turkish Airlines Denied Me to Board Despite Timely Arrival

Ticket numbers: 2352208961678 and 2352208961679. Return flight from Istanbul Airport. We were not allowed to board the plane 18 minutes before the flight. I was with my spouse. The doors closed 20 minutes before the flight, and the cabin crew said 'do not let them in'. Check-in and passport control were completed hours before. It was clear from the system that we were ready for the flight. There was no announcement or similar warning! Please review the video footage from that day. It took longer for them to find and unload our luggage than it would have to let us in, and the plane doors were still open. They forced us to buy tickets for €642 and still did not let us in. We had to take the second flight. 10 minutes before the second flight, 5 more passengers were let in as the doors opened. If passengers are not allowed 20 minutes before the flight, why were passengers allowed 10 minutes before the second flight? When we were coming from Germany, we waited 20 minutes for another passenger and took off with a 40-minute delay. Are the rules dependent on the cabin crew's mood? I kindly request that this be checked with video footage. I have a video showing that passengers were allowed in 10 minutes before the flight.