Our general guidelines are that if the photo could potentially give away the model's identity, then a release is needed. Even if the model’s face is not clearly visible there may be contextual factors that could make them identifiable. Such as unique outfits or clothes, tattoos, silhouettes, locations and photoshoot settings. These must all be taken into consideration.
Please keep in mind that silhouettes, where the facial lines are visible from the side, will also need a release when the person is the main subject of the image
Here's an article that can explain a little further: https://www.eyeem.com/blog/do-you-need-a-legal-photo-release/
If you’re having difficulties uploading your releases please use the link below for reference.