Prores still flickers in M1 Mac Ventura

I wanted to start a new discussion because this is not the green/magenta flicker but a problem with the luminance level. 

I finally decided to bite the bullet and upgraded the M1 Mac Studio to Ventura and tested the latest AE update. Prores 4444 and XQ still flicker in After Effects V23.6.
Prores does not flicker in AE V23.2.1, so it's something in the software.

Here are the settings:
Hardware acceleration is disabled both in import and export.
Using Mercury GPU Acceleration (Metal).
Project color depth 32 bits.
Color Space: None and Display Color Space: None
Clip color space: Preserve RGB
(No Color management setting makes any difference.)

Add an imported Prores 4444 clip on the timeline.
Lower gamma to make high values more visible.
Press RAM preview.
The frame you started from, and the first few frames on the timeline have dropped luminance level.

The rendered video clip has flicker.
Note: When I set the sampling quality to low, Prores does not flicker. In macOS Monterey, there was also a slight banding visible in the RAM preview. (Upgrading to Ventura did fix that.)

I do hope somebody can finally nail this problem.
I cannot use any AE version above 23.2.1. Clients will not accept these results.
Is it possible for anybody to confirm their M1 Mac behaviour, please?

I have attached a screen recording if someone wishes to try to repeat the problem