In byte stuffing, a special byte called the escape character (ESC) is stuffed before every byte in the message with the same pattern as the flag byte. If the ESC sequence is found in the message byte, then another ESC byte is stuffed before it....
There is nothing preventing you from changing the wrong bits in the bit stuffing approach (other than each time checking dynamically which costs computational cycles). The record-approach makes it impossible to accidentally change the wrong bits. ...