serial numbers on individual airpods showing as invalid on apple's website

Hi all, I recently bought airpods pro. I verified the airpods using the serial number present on the lid of the case and it was authentic. However when I check the serial numbers printed on the individual airpods, apple shows that they are invalid. can someone please help me know what does that mean? I got the authenticity of the charging case verified from the authorised reseller, but why does apple show that individual serial numbers of both the airpods are invalid?