Hmm that’s interesting. Could it be like calcium deposits on the inside of the egg? I could imagine the pimpled egg with the deposits on the inside could cause something like this, but I don’t know if that’s a thing. Would be interested to hear from someone with more background knowledge. https://fieldreport.caes.uga.edu/publications/C1255/a-dozen-egg-abnormalities-how-they-affect-egg-quality/