I had the same problem and I found this soln!!!
- Save the slowmo video from google photos to your device(iPhone)
- Go to 'Photos' App and opent the specific video file
- Click on edit
- Click on Revert>>Revert to Original
Save the slowmo video from google photos ro your device(iPhone) Go to 'Photos' App and opent the specific video file Click on edit Click on Revert>>Revert to Original DoneDone!