Okay, so asking for a friend lol, however I have had the same experience. All bunnies are unneutered, but will be altered in the near future. However…

Friend brought home immature female, to what she thought was her male and female. Turns out, mature “female” (Violet) is a boy!! Violet is almost a year old. Is it possible that exposing him to a female made his testicles drop?? I had the same thing happen to my baby males (All bunnies in question are Flemishes, except for new bunny, which is a French lop.) when I brought home my female. Is this a thing, or is it coincidence? She does not want to breed at all, so sexes are kind of irrelevant, but just a curious phenomenon.