Canning venison and canning soups have very different instructions. So I really can't answer your question without some more information.

Did you follow the 1/2 and 1/2 rule required for soups? 1/2 solids and 1/2 liquid? If the jars were 1/2 solids and 1/2 liquid it would be unusual for the liquid level to fall unless you had siphoning. Was the water in the canner still clear when finished or was the soup liquid in the canner water too.

Was the venision packed raw or cooked? For soups it must be packed cooked.

What other ingredients was in the soup and were they cooked first?

How long did you process the jars? Quarts or pints?

What was the source of the instructions you used?

Dave

Here is a link that might be useful: NCHFP - how to can soups