Ask HN: How does GDPR work with P2P sharing?

Recently I have been thinking about sharing images with friends over messaging applications. Often messaging applications download images and store them on a the receivers device. As the person sharing the photo, I have little issue with this...I shared the photo after all. However, what if the receiver has some automated backup service enabled which backs up that image to a Google service or other backup service. Now I, as a user of the messaging application agreed to the terms and conditions for using that application. However I didn't agree to the terms of the backup and I might not be happy with the data I shared being used in the way. Assuming you fell out with a friend at a later date, could you be liable under GDPR for backing up photos you received from someone else, without their permission?