Export camera pans to jpgs : funky formats

When i export a horizontal or vertical pan from my animatic
the jpgs come out all weird: https://snaptube.cam/ https://9apps.cam/
not in the filmratio i’ve set for the project
but with extra space around it and in any ratio possible.
This doesn’t happen with truck-in or outs.
i’ve tried a bunch of export parameter combinations
but now i’m lost

.