Time Machine- backs up files if they are just opened - not even changed?

I Time machine my MacBook Pro running High Sierra very day. I noticed if I simply open a QuickTime movie and view it (even just for a few seconds) Time Machine backs it up again in the next backup! No changes or anything, just open quit the movie - and it will rebackup! I have an App, "Timetracker" that after a Time Machine backup - it'll show what files were Time machined! Does Time Machine recopy and back up files when they're not changed . . . but simply opened and closed? I'm noticing with Final Cut Pro the same thing is happening! Simply open a Library - and Time Machine will backup sometimes several gig, even though I've not made any changes?

Or . . . does Time Machine just look at the date a file was opened . . . and if it's a newer date, it automatically re backs up the file?

I'm hoping there's an easy answer here! 🙂

Thanks, Larry