removing camera dust spots

You can try:

Sensor Dust Spot Remover (install as an Effect)

https://fcpxtemplates.com/?smd_process_download=1&download_id=23253

Add one for each dust spot. Use the OSC and the "target" to adjust the size of the spot remover area. Turn off the target to work on the spot.

If you need more than the Amount slider shows, you can click and drag up on the number to increase the amount. You shouldn't need to — the idea is simply to disguise the spot as inconspicuously as possible.

Keep the Radius small, Soften Edge up to about 50 and Amount to whatever is required to disguise the spot.

There are other methods you could try (Gaussian effect + shape masks for one)... let me know how the spot remover works for you.

Tried all hacks using the mask tool , clone tool and other methods but due to the dynamic moving nature of the clip I am unable to sort it.

I am also close to Irfan Sait's method. You'll probably use shape masks, Gaussian blur, tracking (keyframes), and exposure adjustments.

However, you won't know the result unless you try it with the actual file. Can I try the file if possible?