Round light wasn’t on plane aware app increased brightness traveled southeast faded away

Grandson and I were looking at the stars in between races at the dragstrip. He noticed a bright white perfectly round one moving from the northwest. I looked on Flight Aware and Planes live but it wasn’t on there. We were at a dragstrip and it was too noisy to hear if it had any sound. Appeared to be over 5000 feet traveling southeast at maybe 250-300 mph and we watched it travel across the sky. It was very bright and 30 seconds before it faded away it became brighter, dimmed to normal before it faded out. I thought it might be some type of military aircraft but I took a couple of pictures anyway. The pics were taken with my iPhone 13 and they raised my curiosity. Maybe it’s just the way the camera works taking pics of light when it’s dark out but it seems odd to me. A few minutes later i saw an airplane fly close to the same path but appeared to be at a higher altitude but it didn’t appear on either flight app i have on my phone. The apps did show aircraft but not real close to where we were. My grandson is 6 and I’m a 57 year old area sales manager.