Shaking the phone may flip out the camera slightly. How much it will flip out depends on how much you shake it. So in theory, yes, it can retract a little bit in your pocket even though this has only happened to me on few occasions.
To have a small vertical play is normal but if your play is larger than normal is hard to say. Yes the camera may vibrate when the phone vibrates. Of course it makes sounds when you tap it hard with your finger on the top of the phone. Its the design because we couldn't fit two motorers inside. It's a phone and space is very limited.
Is this a problem? Well it's up to you. This is not a normal phone so don't expect it to behave like one. You need to question, why does this bother you so much, why does it matter?
I believe that most people care so much about the sounds and how it might flip out because they are worried that their unit is faulty or that the camera might stop working. They worry that if there is a small play now, then it will be even worse in a year.
Well, I can give you comfort in that the behavior is perfectly normal and it will not get worse. We have tested this camera extensively in very rough conditions. So when you show your flipping phone to your friends and they comment about the sounds coming from the module, then you can comfortably answer them that it's not a problem. They will most probably reply that they would't buy a phone that makes sounds like this but then again, this is not a phone for everyone. We're not trying to make a Galaxy S10 or a P30 Pro. This is a phone by nerds for nerds. A phone that does things differently. Things that no other phone can do. This is why you bought it and you should be proud of your choice. We're proud of ZenFone 6 and what we achieved. We know it's still not perfect and we're going to continue improving the software to make it even better. We want all ZenFone 6 users to be super happy with their choice and proud to own a ASUS phone.