It is not ideal but it is fairly common and the pickles are still quite safe to eat. The problem is caused by the air still trapped in the fruit. That makes the fruit float. Plus the fruit absorbs some of the liquid in the jar during processing so the liquid level falls off. Over time as they absorb more liquid they will sink a bit but if any remain above the liquid they turn to darken in color and aren't appealing. Just pitch those few when you open the jar.

The only way to prevent it, or at least reduce it is to cook the fruit just a bit longer to force more of the air out of the fruit. Then when you pack the jars put a few less pieces of fruit in and a bit more liquid keeping the same headspace. That way more of the pieces remain covered.

Dave

Thank you Dave!