Looks like something got dissolved in your solution. It could be rust or part of the lid dissolving. Could be an impurity from the lye, jar, lid, or even your hands that got in the water and changed color when the lye was added. If I had to take a wild guess, I would say you shook that jar up after adding the lye, and that's when the color change happened. Those lids dissolve pretty readily, and have dyes and an outer protective layer and rubber in addition to the metal. I've watched those lids slowly dissolve in to rust and plastic with just heat and time under neutral water. Try a clear glass stir rod or just carefully swirling it by hand without a lid and see if it happens again.
Life is effort and I'll stop when I die!
21:26:26 ‹Adept1›It's as close to a fact as you can get
Loose lips cause bad trips.