This kinda looks like an issue between lemmy and kbin. The issue is present on the lemmy ui as well. The ?format=jpg&thumbnail=96
parameter being there doesn't have an effect here. The issue is the thumbnail_url is reported wrong. You can see that here. The thumbnail_url should be: https://kbin.social/media/cache/resolve/entry_thumb/60/a4/60a45b8ff88b1b2e3a0f77b701feb323c5bbfb7ceeb75154ea7df5d6eea15ef8.jpg
We could try and use some regex to lookout for kbin images and rewrite the thumbnail_url, but it should probably just be fixed upstream.
Found this github issue which might be related: https://github.com/LemmyNet/lemmy/issues/3775
I agree, the search results should default to sort by new. Regardless of what your default user setting is. This is how it works on https://old.lemmy.world