Crazy how I’ve been using the same 7 Plus for over a year now, though I haven’t checked my camera lense for dust yet.
I’ve had my iPhone 7 for a year now and it still looks and operates like a brand he’s phone. My Tempered Glass hasn’t even had to be replaced yet. My case has been replaced because the rubber on it tore from wear and tear but no biggie.
To the OP: you’re looking for issues that don’t exist. Just stop because I can promise you the majority of things you think are wrong are indeed normal. Your battery health for example; it’s fine. It’s within the limits of what Apple says is a battery in good operating condition. I wouldn’t expect a refurbished phone to be at 100% and I’d be happy with 97%. Now, if you were having he battery replaced on your phone and paid for it to be placed in your device, sure you should get a 100% battery. But refurbished? No way. Besides, you can’t guarantee the application you’re testing with is 100% accurate either. Just relax and enjoy the phone - life isn’t all doom and gloom you know.