some reasons someone can be AMAB transmasc:
Nonbinary man
Androgyne person
Multigender person that has a male gender
Genderfluid person that has a male gender
System member who is transmasc in a body assigned male at birth
System member who is cis male in a body assigned female at birth
Intersex person assigned male at birth
OB/GYN was sleep deprived and checked the wrong box
Whoever was entering the records let the form autofill
Someone ticked the wrong box during manual digitization of hospital records
Someone wrote the wrong thing on the form while entering records
The dropdown on the records software glitched
The handwriting on the birth certificate was especially unreadable
The OB/GYN had a really thick accent and the nurse wrote down the wrong thing
The computer storing the records was hit by cosmic rays and flipped a bit, and error-checking propagated the error
Nurse entered the wrong twin's data
The doctors confused the children of two people giving birth on the same day with the same legal name
The midwife attending a home birth doesn't speak English and there was a miscommunication in translation
The midwife attending a home birth forgot to file a birth certificate and there was a miscommunication
The clerk filing the birth certificate couldn't understand the parents' accents
Acquired error at the printer
Stamp was sideways
Miscommunication between departments
Machine translation error
Error in translation due to an amateur translator
Translator thought Portugese was Spanish
Translator was sleep-deprived
Translator was off-duty and the nurse had to guess
OB/GYN was Deaf and the nurses didn't know enough ASL
Someone misclicked and didn't notice
"Well, okay, I know these records are in Ukrainian, but ΠΆ is a fancy M, right?"
Server sync issues
Misplaced packet
Pen slipped
Records got corrupted, had to be re-entered from memory
Records got water damage before being digitized
Some other impossible-to-trace clerical error
Probably plenty of other things not listed here
