I've recently received XPS 13 9360 (FHD, i7-8550u, 16 GB) and there is DBC problem. 
Almost everything has been tried to disable CABC:
0) Reset PC
1) Update BIOS (2.19.0)
2) Update Windows 10
3) Update all drivers from SupportAssist
4) Install the latest official firmware update for disabling DBC (https://www.dell.com/support/home/en-us/drivers/driversdetails?driverid=312k3&oscode=wt64a&productcode=xps-13-9360-laptop), but when I launch PanelFW_DBC.exe and click to "Disable DBC" I get an error: 
[QHDFW_DBC] The system without Intel Gfx driver installed
5) Update Intel UHD driver (30.0.101.1340 from Intel website), but the same error is displaying
6) Change PanecFWConfig.ini: add my Intel Gfx driver version to Win10IntelGfxVer field
7) Go to Registry Editor, HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class\{4d36e968-e325-11ce-bfc1-08002be10318}\0000 and change FeatureTestControl (8200 -> 8210)
Try all these methods (https://www.tenforums.com/tutorials/70157-enable-disable-adaptive-brightness-windows-10-a.html)

I know DBC can be disabled, because I did it in 2019 with my XPS 13 9360 (FHD, i5-7200U, 8 GB), but how? I can't remember. Then I tried to downgrade BIOS and Intel UHD driver to 2019 version and BIOS did it unsuccessfully, because of ME updating error 0x00002236.