Some fonts made for use with pcs built the "0" character far more squared at the sides, like a rectangle, plus the "O" character extra rounded. A further difference is manufactured in falsification-hindering typeface as used on German motor vehicle number plates by slitting open the digit 0 over https://financefeeds.com/tradeweb-reports-trading-volume-surge-by-33-3-driven-by-rates-and-credit-activity/