I didn't use vinegar, only very warm water, and I rinsed mine and rubbed pretty hard with my fingers. The dark terracotta bloom came off, and probably some of the finer speckles. But really mostly they didn't budge. Mine are Welsummers.
View attachment 3388299View attachment 3388300What breed are laying the speckles for you? Do you have pictures of the eggs? How much vinegar are you using? How hard are you scrubbing? So many questions...
Pictures are of two different eggs, one similar to the one I washed, just to show the color difference of the dark bloom that does rub off. The egg that remains has gone pale, but is still brown, and still speckled.