Thus bug in https://bugs.kde.org/show_bug.cgi?id=198463 must have come back. If my brightness is down all the way (working at night) and the laptop goes into low power mode, the brightness goes up to the low power setting. It should use the minimum of the two settings (current and low power setting). Thanks!!
rm@xps:~$ uname -a Linux xps 4.8.0-41-generic #44~16.04.1-Ubuntu SMP Fri Mar 3 17:11:16 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux jrm@xps:~$ lsb_release -a LSB Version: core-9.20160110ubuntu0.2-amd64:core-9.20160110ubuntu0.2-noarch:security-9.20160110ubuntu0.2-amd64:security-9.20160110ubuntu0.2-noarch Distributor ID: neon Description: KDE neon User Edition 5.9 Release: 16.04 Codename: xenial jrm@xps:~$
*** This bug has been marked as a duplicate of bug 362831 ***