4.5 .flv video weighs 47 GB when a 2 hour video of the same game weighs only 11.4 GB?

[Lernos]

As stated in the title, I've been recording some Rimworld footage while playing with friends, using the Game Capture mode. Here are my settings that were not changed between recordings:
Output Mode: Advanced
Recording Format: Flash Video (.flv)
Video Encoder: NVIDIA HVENC H.264
Audio Encoder: FFmpeg AAC
Rate Control: CQP
CQ Level: 20
Keyframe Interval: 0 s
Preset: P6: Slower
Tuning: High Quality
Multipass Mode: Two Passes (Quarter Resolution)
Profile: high
Look-ahead: No
Psycho Visual Tuning: No
GPU: 0
Max B-frames: 2

So, we have two videos with the exact same setup and similar gameplay from the same game. However, the 2h 11m video weighs 11.4 GB, while the 4h 27m video is a whopping 47 GB, which, in my humble opinion, is twice the size it should be. What gives? What settings can I change to get my video size to be consistently more like the first 2 hour one?

 

[qhobbes]

With CQP you are selecting a Quality Level (CQ Level). The lower the CQ Level, the higher the quality, the higher the file size (assuming resolution, frame rate and content are the same/consistent). I have my doubts that the content of a 2h 11m and a 4h 27m Rimworld footage is consistent.

If you want consistent file size, you use Constant Bitrate.