I’ve looked through the forum and haven’t seen anything like this happening elsewhere, so I thought I might as well ask…
I am getting undesired screen dimming when I plug in my laptop while it’s on; i.e., I’m working without the cord, notice the battery getting low, and I plug in.
For what it’s worth, “dim screen while inactive” is not enabled.
Have you checked your BIOS/UEFI settings? Many devices have settings for display brightness here too, which then get synchronized/overwritten with the settings of the operating system. So maybe the interface for that is not working correctly.
Honestly, I didn’t even think of it… I’ll check & circle back. Thanks for the idea!
There doesn’t seem to be anything in the BIOS that deals with this at all. FWIW, I’m running Fedora on an Asus ZenBook UX425IA.
Pretty decent device 
Can you please give us some more information about your fedora installation?
Is it a minimal installation or a standard fedora workstation installation?
What desktop environment are you running?
Thanks… When I had to replace my old Asus ZenBook because the kiddo knocked my coffee onto the keyboard, I committed to one with a Ryzen chip & I liked this one the best of those.
Nothing fancy, everything standard in the install… Workstation with GNOME.