Removing Waffle Grid Pattern

[Jean-Luc]

When the FFT plugin is applied to your image, the result doesn't show "star-like" areas. So, it cannot be corrected by that plugin.
Here is an image where "star-like" areas are visible.

The repeating pattern is concentrated in the 'star-like' zones. To remove the pattern, we manually remove those "star-like" areas by painting on it like this:

And we apply the iFFT plugin to reconstruct the image.

If you cannot obtain a better original image, it cannot be corrected by the FFT plugin.

PS: did you see my message from Stat Aug 14, 2021 12:13 pm? containing a different image?

[Jean-Luc]

Here a correction made manually:
- Soften Brush on the face without touching the eyes, nose, mouth and chin
- Select the background and applied a Gaussian Blur
- Some cloning here and there

[aksarben]

Thanks for the clarification, Jean-Luc. Your description of the steps was much clearer than what I found elsewhere online. I appreciate your time & patience with a novice!