I only noticed this minor visual bug when jumping from a 1080p monitor to 1440p with the following parameters:
- Scale factor: 1.0
- Status bar scale: 6 (or scale to fullscreen), 8
- HUD preserves aspect ratio: true
The pixel row in-between the game view and status bar is part of the green border, and is most apparent against Doomguy's hand or other high contrast images.
I've observed it in GZDoom 4.5.0, g4.6pre-50-gd8164e005 (default config besides the parameter changes and texture filtering off), and even the earliest copy of GZDoom I had left (g2.3pre-196-gc3ced58). It seemed to only occur on all ZDoom based source ports I have, it didn't for example occur in PRBoom+.
It's probably the definition of nitpicky but it has driven me insane since I switched monitors.
GZDoom 4.5.0 (fullscreen/zoom in to see the gap)
PRBoom+ (no pixel gap)