Apple wants all developers to update their apps to 64-bit. It’s not an unreasonable request given that Apple’s iOS devices went 64-bit back in 2013. Luckily, the warning only appears once, not every time you launch the app. I’m unsure if the warning would pop up again after a cold boot for those apps. Only two of my apps have given me the warning so far; all the others I think are 64-bit. The first was Cracked (the popular humor site’s app), which is actually a complete mess, it can’t even play the site’s funny videos anymore, and this one: What 32-bit apps have given you the warning? Do you notice compromised performance in those apps? Heck, I spend like 80 - 90% of the time in Low Power Mode, so my phone is already being slowed down (but I don’t really notice it, which is why I user this power-saving feature so frequently). Here’s an article which goes into more detail about the “situation."