I had similar thing over the weekend with a Black Neon. also was often very pale in color.
A "few" weeks or so a go (?,)
maybe more, I was looking at pics of my tank from 4 years+ ago... in that pic, behind the betta, was a group of black tetras and 3 Ember tetras.... I realize how old they were now.... had 2 blacks and 1 ember left.. .well, now it's one and one, but they have had a good life! Took this pic in March, so it has been a "couple weeks ago" before quarantine!
A "few" weeks or so a go (?,)