>>1607671I applied the "low pass" blur filter to HALF of your image so you could see what it does.
Looks effective to me.
Unfortunately, I'm using Corel PhotoPaint rather than Photoshop. I know that puts me in the minority. But PS ought to have some equivalent.
Help defines it as:
• Low pass — removes sharp edges and detail from an image, leaving smooth gradients and low-frequency areas. The higher the settings you specify, the more image detail is erased.