[EDIT]: The issue has something to do with Last Pass inserting itself into the DOM before the image has a chance to unload. Disabling the Last Pass extension fixed the issue in all cases for me.
I spent all this time digging into this issue before solving it, so I figured I'd at least share the journey with everyone.
I've found a strange issue where a scroll bar will appear, showing over 200px of blank space under my Perspective view (which I had designed to be full screen, no scrolling). The scroll bar disappears after a browser refresh, but reappears after logging in.
Not Logged In
Logged In
Fixes
I've noticed that if I remove this img tag, the problem goes away.
Refreshing the screen (F5) also removes the image.
Without Co-Branding
Disabling Custom Branding in the gateway doesn't fix the issue either. Instead of my customer's branding, I get Ignition's branding in the same spot.
I'm using Ignition v8.1.27 (b2023042509).