Iphone Exif Data

I was looking at an Iphone 7 using Cellebrite software. The exif data for a video showed the date the video was created and a modified date. The modified date and time was the time the phone was searched by an agents. Can someone explain why the modified date changed? I am wondering if the modified date changed because the video was downloaded from ICloud while the agent was looking at the phone. Any help or reference to some research would be greatly appreciated. Thank you in advance