Hello after my latest Distro update it showed me this 2 new errors, directly after a fresh boot:
Jun 05 04:30:40 koboldx-z170 org_kde_powerdevil[1864]: [ 1864][ 1.327293] Time since library initialized: 1.327293 seconds
Jun 05 04:30:40 koboldx-z170 org_kde_powerdevil[1864]: [ 1864][ 1.327295] Extra delay starting dw_start_watch_displays: 0 millisec
What makes you think they’re errors?
Well, i could have a wrong viewpoint,
I just use this command for my journal:
journalctl -p 3 -xb
I always thought this command mainly highlight error’s in red color from journal, but you think this is a normal info?
I just wanted to report this output, just in case… I’m using the new KDE Plasma version since 7 days and besides a single game freeze (i had no other problem’s yet), while i open in background with alt+tab in SMPlayer a video file on my PC and the only info showed up again in journal was this, i was thinking this might is somehow related and can’t hurt to report this error/info or what ever it is.
But since my system is too 99% stable in most games and playing youtube video’s in background while gaming is no problem either. So im actually not 100% sure about a error or a warning 
PowerDevil incorporates libddcutil, which also prints its own log messages as part of PowerDevil’s logs. It is likely that the maintainer of libddcutil added extra info that would help him with debugging other people’s reported issues.
In particular, the line appears to be about libddcutil’s continuous display-watch functionality, which helps PowerDevil to deal with monitor configuration changes (for its brightness configuration functionality).
I wouldn’t assume anything questionable from this, unless you are actually seeing issues with your system’s behavior. If you’re especially motivated, you could probably search for the text of this line in libddcutil’s source code on GitHub, and find out why exactly it was added there.