Unfortunately, you can't do much. Brightness flickering with adaptive sync enabled happens due to monitor's brightness levels across it's variable refresh rate not being properly calibrated by the manufacturer.
You can try to disable sync at certain most "problemtatic" refresh rate points with CRU (ex.: limiting it to 120hz-144hz) but this would require time for trial and error and might not work stable in the end.
Options to avoid tearing with freesync disabled (adaptive sync) are vsync and enchanced sync. Both will remove tearing only when the frame rate of the game matches or exceeds the display's refresh rate. But even using 9900k&2080ti it's impossible to get stable 144 fps in most modern AAA games using 1440p resolution.
Honestly just return the monitor back to the shop if it is still possible and get the model that doesn't suffer from this issue.
Based on specs: 32 inch, 1440p, 144hz, VA, thin bezel, decent pixel response time and similar price - i can recommend getting LG 32GK650F.
oh perfect...this is really disappointing. I have already trashed the package... there is no way they will accept it back now. What if i set the monitor refresh rate to 110Hz and play games with VSync on? My card can maintain 110 fps in most games on medium settings
It depends on how much you can tolerate that.
There are supported refresh rates under Display section in Windows settings (60hz, 75hz, 100hz, 120hz, 144hz, 165hz) - depends on the monitor, connection and gpu. You can use vsync (ingame option or forced in radeon settings) with those.
Applying vsync with custom refresh rate (110hz) technically should work but you have to be ready dealing with issues and inconcistencies with certain applications.
You might be able not only to return that product but even RMA it due to being faulty (flickering). Worth a try in my opinion, but it's up to you!
To be honest due to the fact that i have 110+ fps in most games i don't notice so much flickering with Freesync disabled except in RTS games where the camera is moving only in X or Y axis, but i would prefer it to work with Freesync on without any problems.
I will see what i can do with the RMA but i am not that positive.
I just got the same monitor and I have the same problem. I have a RX 5600 XT. I had an older monitor with Freesync1 (27" 1080p 45-144Hz Range) on it and I never ever had any flickering with it. After looking around I found many many complaints about this problem with other monitors also and not just Dell. It seems to be a problem with VA monitors with freesync2 and possibly with Samsung LCDs.
AMD, you need to do a better job with this freesync stuff. This many complaints is unacceptable.