126 Kbps audio bit rate instead of 128 kbps!

Hello everyone, I have a problem with the audio bit rate when I set 128 kbps at the end after finishing the encoder, it shows me the 126 Kbps audio details! I'm wodering why ? Do I need to set something to show me 128 kbps? Can someone help me please! 🙏

My Adobe Encoder export settings!
Video -1080 x 1920 p / 29 fps
Audio - AAC / 44100 HZ  / Bit rate-  128 Kbps