rendering video at higher resolution than physical screen

hi

your project is really cool, thanks for that.

I am on Ubuntu 20.04 and I am trying to render a few videos.
I have noticed the following pattern though: if I render a video in a resolution which is higher than the one of the windows context being displayed at render time, then the output video is not correct, like if multiple windows were stacked altogether to form a full frame. I have a 1920x1080p physical screen resolution.
fyi when I render output at 720p the output looks fine.

In the output example below, I did try to render a 4k video, but you see the output is not as expected...

Is it something that others encountered? Can I fix it somehow? (can I de-activate the screen render of the shader ? can I use some special params to help with this issue?)
thank you

Start by reproducing the issue on Ubuntu 20.04 with a 1920x1080 physical screen, comparing the working 720p render with the broken 4K render. Use the attached output example to investigate the window-stacking behavior; done means higher-resolution video renders as one correct full frame.

Written by the indexing model from the issue text.