SUMMARY
When recording a video (with the recorder plugin) if you change the canvas size/proportions, in the final render it gets stretched

STEPS TO REPRODUCE
1. Create a document and turn on recorder tool 
2. Draw something
3. Resize your canvas to another aspect ratio
4. Go to recorder docker, render the video 

OBSERVED RESULT
The video will be stretched out to match the original aspect ratio 

EXPECTED RESULT
The frames shouldn't be stretched out to match the original aspect ratio, Krita should be able to maintain each frame in their own ratio and add black borders to those that have different proportions.

For a visual explanation:
https://imgur.com/a/OQoCbTt

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: elementary OS 5.1.7
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION