Im no expert, but have been canning russet potatoes for a few yrs. As long as they’re sealed, they’ll be fine. Siphoning happens. Make sure to debubble as best you can. I do raw packed, after soaking and rinsing. Russets are starchy, yes, reason soak a few times. They’re my husbands husband’s favorite. They do hold their shape and are not mushy. I open jar, drain and quick rinse and can make a decent potato salad, home fries, etc. I canned 10lbs yesterday, I had some siphoning in a couple of jars. Have another 18lbs that I prepped before bed that I have to can up today. Didn’t plan on 18lbs, they were going to go into basement to replace the 10lbs, but the “eyes” got it!!