That awful gradient that happens with the gaussian blur.

The reason for banding is always reduced bit depth. 8 bit data will always show banding in smooth shallow gradients like this.

But what most people don't think about is that even with a 16 bit document, your display pipeline is still 8 bit (unless you have a 10-bit capable monitor/video card), and furthermore, there are several components in that pipeline that can introduce banding on their own: 8 bit output from the video card, corrections in monitor calibration, a faulty monitor profile, and the display panel itself.

Most inexpensive panels are actually 6 bit natively (all TN-panels used for gaming and office), and the 2 extra bits achieved by dithering.

All these potential sources for banding are cumulative, they build on top of each other. The final result can be very irregular banding with strong color components because the channels are affected differently.

In short - if you see banding in a 16 bit file, it's in your display system.

Great job guys thanks you all! 😄

You could try adding noise or using the splatter filter and then adding a little more blur or you could use 16 bit instead of 8 bit to lessen the banding.

I agree with @c_pfaffenbichler.

You could also try adding just a little noise. This can do a great job of breaking up those lines.

Try working in 16bit.