xorg-server dropping default suid
Starting 2020-07-15, stable keyworded x11-base/xorg-server will default to using the logind interface instead of suid by default. resulting in better security by default through running the server as a regular user instead of root. However, this will require our users to use a logind provider such as elogind or systemd. The systemd users and those who are not using systemd but use desktop profiles can stop reading here, as they already have a logind provider enabled.
Others, who have neither systemd or desktop profiles enabled will be required to globally enable 'elogind' USE flag and update the system
# emerge --newuse @world
Afterwards, one will need to re-login, so the PAM can assign a seat. One can confirm that a seat has been assigned upon login by running:
$ loginctl user-status
Users who do not wish to use logind interface or have rare hardware that does not use KMS and because of that, require root privileges to operate, can manually re-enable 'suid' and disable 'elogind' USE flags in order to preserve the previous behavior. However, please note that this is heavily discouraged to run X server as root due to security reasons. The 'suid' USE flag will remain as optional opt-in for the need of legacy hardware.