What is the major drawback of single bit parity check method for error detection?

The major drawback of the single bit parity check method for error detection is its inability to detect errors when an even number of bits are flipped. For example, if two bits in a data unit change, the parity may still appear correct, leading to undetected errors. Additionally, it can only indicate whether an error has occurred, not the location or nature of the error, limiting its effectiveness in error correction.