Using h264_nvenc to save my project. If I set quality settings the result file is:
60% quality = 5.3mb
70% = 12mb
80% = 18 mb
90% = 18 mb (!)
100% = 3 mb (!!!)
So as you can see, after 80% quantizer stops work properly and do not increases bitrate and even significantly decreses it on 100%
Used settings:
1280 x 30fps 264 H.main profile
System: windows 10 x64 ver 1909
Shotcut 19.10.20
The same settings on CPU encoding works fine and linearly increases file size