There seems to be an issue in DaVinci Resolve with the contrast displayed on Macs compared to the exported data and played back using some other tool.
Let's say we grade the footage – we set the levels and export the clip as ProRes 422. Once it's done we play it back in, let's say, VLC and the contrast differs.
I experienced the problem on iMac and MacBook Pro, but I believe it happens also when using Apple Displays.
The quick fix is to uncheck the Use Mac Display Color Profile for viewers option in the settings:
Once the option is removed the preview in DaVinci Resolve gets fixed and looks the same as in the VLC after the export.
Here's the before & after:
It's easy to fix but before I found the solution I spent some time trying to figure out the root cause. Hope this post saves you some time.