Encoding bitr rate is below the setting
BUG: Bitrates of exported files are significantly lower than the bitrate settings. Setting a Constant Bit Rate of 20Mbps yields a bitrate of 4.3Mbps on the finished file. The quality of the image is irrelevant as many media outlets have minimum bitrate requirements for deliverables.
Antoine (Autokroma.com) commented
Would you have file sample about that ?
Sometime it's hard for the encoder to put more bits into the file as it's not always necessary...