In the new render settings in Version 22.04.0 is a bug!

The error only occurs when a new preset is created.
When you click on Custom Quality, there is a slider that goes from Low to High.
At 100% High, you have crf=51 and the quality is very poor.
At 25% Low, you have crf=12 and the quality is very good but the file is huge.

I you switch off Custom Quality and then select the value in the Video tab in Quality itself, e.g. 20, then the render setting will work logically and correctly.

The totally tricky thing is that the slider for "Custom Quality" behaves correctly with the standard template in Generic MP4H264/ACC.

My custom preset: be sure to switch off: „Cusotm Quality“ !!
Video: Container: mp4, Scanning: Progressiv, Codec: libx264, Rate Control: Contrained VBR, Bitrate: 0k, Buffer Size: 0 KiB, Quality: 20, GOP: 15, B Frames: 0
Audio: 2 (stereo), Codec: aac, Sampel Rate: 48000 Hz, Rate Control: VBR, Quality: 0
Ohter: Speed potions: preset=slower, Additional Parameters: movflags=+faststart

This has been fixed now

In the current version 22.04.2 the slider for the quality runs in the right direction.
And the default, when restarting the program, is always this: Custom Quality > 3%, which is a crf of 45, so completely unusable.

But there is more wrong. With the preset: Generic > MP4-H264/AAC Quality 84% gives a crf=20.
And with a custom preset, Quality 84% makes a crf=9.

(In this and another bunch of bugs I really start to wonder if there is any quality control left in the KDE-project?)

I have lost a whole edit (I was stupid enough to delete the sources after a successful edit, checked, stupid me, only on the video) in the audio department. While video is fine, audio remained mum. Here it is:
Metadata:
handler_name : VideoHandler
Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 2 kb/s (default)

I can guarantee that I never set a default of 2 kb/s.

While a slider for Custom Quality is fine, I wouldn't want the average user having to understand CRF values. And also, the only 'feedback' being the changes in the rendering parameters line further down. "Compromise file size versus quality" isn't most helpful when a change of just 6 between 0 and 51 means around a duplication.

I hope your losses are not infinite.
I think that the render settings in Kdenlive 22.04.3 are finally in order. Is everything working again for you as it should?