No constant bitrate control x265 HEVC

Hello everyone

Despite using CFR or CQP, the file after rendering has a very variable bitrate. For example: the value can fluctuate from 20 to 100 Mb/s. When I use NVIDIA HEVC (CFR or CQP) there are no such large fluctuations.

In the case of x265 HEVC I used the default settings, or presets. What am I doing wrong?

For example, here are the graphs from the original DJI pocket 3 file and after export

Green line: original DJI file
Red line: file after export

I use Voukoder 13.4.1 + Magix Vegas 22

I got advice from various sources and managed to eliminate large fluctuations in bitrate using the following parameters:

crf=22.000 level=5.1 preset=slow profile=main10 x265-params=vbv-bufsize=240000:vbv-maxrate=120000:aq-strength=3.000:psy-rd=2.500:psy-rdoq=1.500:keyint=120:min-keyint=60:scenecut=60:rc-lookahead=50

I'm just not sure if there's anything else that can be improved. Maybe some parameter is wrong or unnecessary?

I have a 4k, 60fps, 10 bit project, files from DJI Pocket 3 120Mb/s and I want to get an output file with a bitrate of about 120M/bs, I don't care about the file size and rendering time, I care about the best possible quality of the resulting file.

I am happy with the current result, but maybe there is something that can be improved?

The image shows:

green line - default X265 settings

red line - my settings

blue line - original DJI file

I don't care about the file size, but I still think about X265 (without sudden fluctuations)

Do you mean CQP?