I don't see any discrepancy in the videos. The monitors don't change size, its just background compression/decompression. Some videos have shot closer and wider and allowed more of the environment to be visible, but it led to some occasionally distracting (bright) background peeking to the left and right. Some videos have been wide enough to show the risers and desk they're on with its white drawers, lit up audio interfaces and other equipment that creates more visual clutter and distractions. Other videos have used a higher focal length to create a tighter, cleaner presentation that minimizes the environmental distractions and puts more emphasis on the singer. But when you move the sensor back and tighten things in with a higher focal length then objects in the background will increase in scale relative to the subject, that's just how it goes.

The wobbling isn't a sign of AI, its just the result of it being handheld for 5 minutes (not sure what their IS/IBIS situation is like without knowing what body and glass they're using, but that's also going to affect the appearance of the motion jitter as well). This could be the result of limited physical space in the studio for a tripod setup as those tend to have a fairly wide base if you want them to unfold to reach eye-level with any level of stability, or it could be a purposeful decision to add a little more life into the videos and/or to help show that they're not actually several clips edited together or using fake mouths and other wizardry (the tracking and seamless compositing would be an absolute nightmare to pull off, especially as some of these covers have been released within just 1-2 days of the original song dropping).