on the latest version of OBS studio, CQP bitrate settings is bugged and tied to your CBR bitrate settings
eg : if you set CBR bitrate to 2000, apply then change to use CQP, no matter what CQP settings you made the bitrate will always be 2000 (CBR settings)
the only way to change the bitrate is to go back to CBR, change its bitrate.
my conclusion is CQP is broken and doesn't work at all since it supposes to automatically control the bitrate but it actually uses CBR bitrate settings.
eg : if you set CBR bitrate to 2000, apply then change to use CQP, no matter what CQP settings you made the bitrate will always be 2000 (CBR settings)
the only way to change the bitrate is to go back to CBR, change its bitrate.
my conclusion is CQP is broken and doesn't work at all since it supposes to automatically control the bitrate but it actually uses CBR bitrate settings.