Hi Aappllee,
Thanks for being a part of Apple Support Communities. It sounds as though, your replacement iPhone 12 Pro Max is displaying the same behavior when swiping up, as it shutters. We might be able to provide a solution to this and at least isolate this much further.
Do you use a screen protector or case on the new iPhone? If so, remove them to test it out.
If you've already had the iPhone replaced with a new one and the same issue occurs, there is a way to isolate the issue between the software, user data, and a hardware issue. When you received the replacement iPhone, did you restore from a backup of the other iPhone? If so, the issue (if data related) may have returned once restored. To test this further, you'd want to restore the iPhone to factory settings and test it out after setting it up as new. Note: You'll want to backup everything important prior to doing this: How to back up your iPhone, iPad, and iPod touch Then you'll follow: Restore your iPhone, iPad, or iPod to factory settings
Once you've set it up as new, test it out. Does the issue persist without user data? In case it does, then you can always restore the backup: Restore your iPhone, iPad, or iPod touch from a backup and see if you can get a diagnostic when you Contact Apple Support
If you determine there is a hardware issue, this can help to find a local service center: Find Locations And this can help you prepare for that visit: Get your iPhone, iPad, or iPod touch ready for service Due to the current conditions, the stores many have changed their hours and/or have limited appointment times. They may also require specific things (like wearing a mask) while visiting.
Wishing you the best, take care!
