But you know where that image size does not look awkward?
I just cropped an image that @Vocino made for me and it looks really good on my tablet. I might try another.
Edit again - I don’t think this new banner is meant to be seen on browser. I think that’s why they hid it on the followers page (it is actually on the following page also) as they did.
If you click on anyone’s avatar with the mobile app then you can easily see their banner image.