Hi! I understand you're experiencing an issue with Snapseed on your iPhone 15 where edited photos lose highlights and look muddy. Let's get to the bottom of this together.

To start, can you tell me a bit more about your editing process? For example:
- Which Snapseed tools or filters are you using when making edits?
- Do you notice this issue right after editing or only after saving and viewing the photo elsewhere?
- Are your photos originally in standard JPEG format or RAW format?

Meanwhile, here are some initial steps that often help with highlight and contrast issues on Snapseed iOS:

1. Review Highlights & Shadows Settings:
- Use the "Tune Image" tool, then adjust the "Highlights" slider to bring back brightness in the brighter areas of your photo. Raising highlights will make bright parts pop better.
- Adjust "Shadows" if parts seem overly dark or muddy to balance exposure.

2. Check "Structure" and "Contrast":
- Increasing structure selectively sharpens details without crushing highlights.
- Adjust contrast carefully; too much can cause muddy appearance but too little can flatten the image.

3. Export Settings:
- When saving, make sure you are exporting at the highest quality. On iOS, Snapseed usually saves in full resolution, but double-check to avoid compression artifacts.

4. Update Snapseed App:
- Ensure that your Snapseed version is fully up to date. Sometimes, highlight issues have been connected to bugs fixed in recent updates.

5. Restart & Reinstall:
- If problems persist, try restarting your iPhone
- If that doesn’t help, uninstall Snapseed and reinstall it. This clears caches and resets settings which might resolve any glitches.

If you've already tried these or would like, I can walk you through a specific step in detail.

Does this sound like what you are experiencing? Let me know how your edits flow or if you want help with particular tools!