When booting Gentoo with the UI interface and Raspian Buster Lite (July 2019 version) on the Raspberry Pi 4 (2 Gigas of RAM) the boot is done perfectly and it is possible to work with the PI.
However when setting
display_rotate=3 on config.txt the screen is very shifted to the right and the boot process hangs.
I've also tried to use
hdmi_safe=1 but it did not work.
P.S. The same screen I use with Raspberry Pi 3 and Raspberry Zero W and I have no issues when rotating.