Yes—what you’re seeing is flare/veiling haze from stray sunlight hitting the lens. A full matte box is usually overkill for a phone setup. Start with the simplest solution: use an appropriate lens hood or shade for the lens you’re using. That often cuts a lot of unwanted light.

If you still need more control, add a small flag (a “French flag” style shade) mounted to your rig, tripod mount, or accessory shoe/foot slot. A DIY version can work fine as long as it stays out of the frame and securely mounts.

For maximum control in product photography, the best fix is often controlling the light rather than shielding it—shoot in a space without window light and use only the lights you want. That eliminates stray sun haze entirely.

So, in order: lens hood first, then a small mounted flag or DIY shade, and if possible move to a controlled lighting setup.