Hello and thanks for your answer!
https://www.asuswebstorage.com/navigate/s/B11ACA4B6B0A41258BDDFD754122D574W
In this link you'll find 2 photos and two videos: one is taken from the standard camera app from Asus, while the other one is taken with Instagram. The quality of the Instagram ones is the same for every other app. You can see 2 things:
1) the photo and the video lose a lot of colour, it's like they get less saturation
2) in the instagram ones you can see some sort of black vertical bars (especially in the video you can see them moving)
This happens with every single app that uses the camera (Instagram, Whatsapp, CamScanner, Skype, etc), so i think this should be fixed with an update. The main problems are those black bars (they're really annoying in the video) and the lack of colour and saturation in the image. You can see that there's also a lot of noise in the photo taken with Instagram, but I think this is because the photo and the video are lighter.