WhatsApp automatically saves media to your gallery. That sounds like a good idea, but when you’re part of multiple groups, this can take up a lot of storage space. Here’s how you can stop WhatsApp from auto-saving images.
Stop WhatsApp from Auto-Saving Images on the iPhone
By default, all photos and videos you receive are saved directly to the Camera Roll in the Photos app on your iPhone.
To disable the feature, open the WhatsApp app and go to the “Settings” tab. Here, select the “Chats” option.