whenever I use blur or mask feather on any solid or imported layer into after effects I get patterns in the layer instead of a smooth finish and those patterns make the whole composition look bad. I tried changing my project from 8bits to 32 bits but it doesn't help much can anyone please help telling me what I am doing wrong.
Looks like banding to me. You can add a very little bit of noise to help break it up a bit, or you can try a third-party De-band effect, such as the ones in GenArts Sapphire or FxFactory / PHYX Cleaner.
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