1/1/1900 is a standard used for any date that is invalid or null. In other words, when the computer cannot read a date properly, 1/1/1900 is used.
A Twitter user named Mike Coudrey falsely claimed that "Photos from the Michigan voter database show numerous “voters” who have the birth year of 1/1/1900. That means they are all 120 years old! This is completely fraudulent and should be grounds for a lawsuit!"
1/1/1900 is a standard used for any date that is invalid or null. Since the birth date on the ballots wasn't legible for the computer to pick it up correctly, the date '1/1/1900' was used for those ballots and the votes are legitimate. This issue mainly arises when there is a human error while entering the date of birth. Therefore, this claim is false.