Audio video out of sync

Hello! I noticed that when I play some videos from the Apple TV app on my IPhone, the audio is never really in sync with the video. There’s a slight delay between the spoken (visual on screen) and sound coming through. The subtitles follow the video. I checked Bluetooth connection, and restarted my phone as well as forced closed the app and updated all software. I’ve tried to see if the compatible SD/HD option was at fault, but nothing works. It’s only some videos and not all. The videos are played in Apple TV app on my phone and are purchased through iTunes Store app also on phone.

Hope somebody can help.