Hi there NoahMeek,
We understand that you’re seeing Screen Time usage of over 12 hours via Safari, though your default web browser is set to Google Chrome on your iPhone and Mac.
Let’s first check to see if the screen time usage is reporting both devices or each individual device. That will at least give us a place to start and see which device is reporting the high usage.
On your iPhone in Settings > Screen Time is Share Across Devices on or off? If it is on, let’s turn it off for right now. On your Mac that setting is in System Preferences > Screen Time.
Let’s also next make sure your iPhone, which you’ve reported as an iPhone 6s, is running iOS 14.4.2. You can check that in Settings > General > About. If it is not, please create a backup and install the update.
How to back up your iPhone, iPad, and iPod touch
Update your iPhone, iPad, or iPod touch
Also, check to be sure all macOS updates are installed on your Mac, making sure to back up before installing any updates as well. How to update the software on your Mac
After that, are we able to determine which device is using Safari for that time frame?
Please let us know what you find out.