It's a valid question/suggestion. This was just how I chose to implement this feature from the start which was to keep the thumbnail and link separate. I think most apps do combine them so that tapping on the image opens the link instead of the image.

When I was designing this I wanted to give a clear way to interact with the link vs the image. Combining them makes it murkier. Eg. what if someone actually wanted to download the thumbnail?

I think combining them definitely makes more sense for optimizing for the most common case though.

I think given the behavior of other apps this is probably a losing battle for me. I'll give this more thought and revisit the design of this.