Sounds like you are stuffing too much into it, or perhaps the wrong-shaped objects.
If the bag is already bulging with nothing in it, then yes the smaller size may fit better.
Or you could move the Revelate bag on and get a custom bag made (by Bedrock Bags f'instance), that fits the frame correctly.
Yeah it only happens with my square plastic food containers in it. Maybe that's the issue, although the very bottom is a spare tube, multitool, and soft bag first aid kit.
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