Hi niels254,
Sometimes, restarting can correct minor issues, so if you haven't done so yet, restart your iPhone.
Since having the latest software can help with overall performance, it's also a good idea to make sure your iPhone is updated to iOS 16.0.2: Apple security updates
Although your device is new, check your available device storage, as low storage can impact performance: About iOS or iPadOS performance on your iPhone, iPad, or iPod touch
Make sure you have enough storage
If your device is low on storage, iOS or iPadOS automatically frees up space while installing an app, updating iOS or iPadOS, downloading music, recording videos, and more. iOS or iPadOS only removes items that can be downloaded again or that aren't needed anymore.
You can check your device's storage in Settings > General > [Device] Storage. For best performance, try to maintain at least 1GB of free space. If your available storage is consistently less than 1GB, your device might slow down as iOS repeatedly makes room for more content.
If you need to free up some space, follow these steps to turn on the storage-saving recommendations built in to iOS or iPadOS:
1. Go to Settings > General > [Device] Storage and read the recommendations that iOS or iPadOS might provide.
2. Tap Enable to turn on a recommendation, or tap a recommendation title to review the content that you can delete.
If you don't see any recommendations—or if you need to free up even more space—you can review the apps on your device. They're listed on the same [Device] Storage screen along with the amount of space that they use.
Tap an app, then choose from the options:
• Offload the app, which frees up storage used by the app, but keeps its documents and data.
• Delete the app, which removes the app and its related data.
• Depending on the app, you might be able to delete some of its documents and data.
Best regards.