Mangione's lawyers are claiming that the search of his backpack was illegal, and attempting to prevent the evidence found that way from being used. https://apnews.com/article/mangione-unitedhealthcare-murder-evidence-backpack-0aa1bad190d798e5ece72a15d72791d7

Will all of the contents of the backpack be admitted as evidence?

If some of the contents of the backpack are deemed not admissible, this will resolve NO. If the backpack is admitted as evidence with caveats where the jury can decide how trustworthy it is, those caveats would be insufficient to make this resolve NO.