Sea Urchin Roe (uni) -- is a mixed yellow and brownish color okay?

It is often very hard to even get uni in many places (which is blamed on sometimes weather and/or sea otters) and even when I can order it, it is not of uniform golden color but sort of mixed. I suspect this might be (my research yields) "vani" which is a mixture of chunks that have broken off and are collected together and sold.

I am not only somewhat picky about looks but even more concerned about safety and of course taste. Years ago, I don’t recall getting anything other than just pure chunks of golden, no brown, uni.

Is the brown just normal color range or is it somewhat spoiled or is it even, shudder, part of the sea urchin that is not actually uni?

I did find this by searching for sea urchin roe, not "uni" and it sounds like brown is not a good thing: https://www.researchgate.net/publication/223038425_Factors_causing_Brown-colored_gonads_of_the_sea_urchin_Strongylocentrotus_nudus_in_northen_Honoshu_Japan