I've downloaded and looked your video.
It is usual video with constant frame resolution 1920x960.
Base video source have this resoution and only small part of scenes has 4:3 screen aspect ratio and black borders from left and right sides.
To avoide resolution changes best solution is to disable SVP option: Video frame > Detect and cut off black bars
Or you can open Advanced controls option of Video frame menu, press and hold button Black bars detection and select option: One time only