Same problem here. Found a mitigation that works:
https://github.com/TillmannBerg/Ubuntu-Dell-XPS-15-2019#screen- brightness-oled -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1862835 Title: [Dell XPS 15 9570] Unable to change laptop screen brightness or keyboard backlighting To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1862835/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
