Hello Jamais,
Thank you for using Apple Support Communities. Based on your post, your iPhone 12 Pro Max camera shakes when using 1.0 and 2.5 lenses. We'll do our best to assist.
It might be good to confirm if this happens with the front and rear cameras on your iPhone. You can switch between the cameras to test it out.
Make sure you don't have any saved settings for your camera: Save camera settings on iPhone
If this continues to occur, then you may want to Contact Apple Support to run diagnostics or bring it in to a local Apple Store or Apple Authorized Service Provider.
This can help prep you for the appointment: Get your iPhone, iPad, or iPod touch ready for service
To locate a service center, select your region and search nearby: Find Locations
Keep in mind, due to the current conditions around the world, some stores may have limited hours or appointment times. They also may require specific things to visit them (Such as, scheduling an appointment, wearing a mask, calling to check-in, etc.).
Wishing you the best, take care!