jds_portugal here's your flight track. For simplicity I have taken a point on your flight near Madrid, at 20:37UTC
At this time the sun was practically due West and about 44 degrees below the horizon. These fit with the condition where we expect to see Starlink flares. Checking on in-the-sky.org shows that there were multiple Starlink Satellites on the horizon around that time. So it is at least 'possible' that you saw Starlink flaring. If you check the videos I posted earlier in the thread you can see what they look like and if they matched what you saw.
