I don't see any evidence of a low graphics mode really being active here. It sounds like the popup you are seeing is wrong.
Also, since you have modern hardware we recommend upgrading to Ubuntu 20.04 if you can. ** Package changed: xorg (Ubuntu) => xorg-server (Ubuntu) -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1929329 Title: low graphic mode To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1929329/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp