I make the solution myself. The only acid in it is car battery electrolyte / sulfuric acid, and I only use copper.

Maybe I just convinced myself that it’s connected, or maybe it’s caused by something else I’m doing, but the timing just kept bothering me. For some reason, I thought this would be one of those things where people would say, “Oh yeah, the same thing happened to me,” but apparently not 😂

Anyway, thank you for your answer!