Hello Kvaris,
Let's use the steps below to make sure both her device and your device are all up to date:
1. Back up your device using iCloud or your computer.
2. Plug your device into power and connect to the internet with Wi-Fi.
3. Go to Settings > General, then tap Software Update.
4. If you see more than one software update option available, choose the one that you want to install.
5. Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If you don't know your passcode, learn what to do.
You can also find those steps in this resource: Update your iPhone or iPad - Apple Support
If both devices are up to date, let's restart: Restart your iPhone - Apple Support
Updating and restarting should help to further isolate a potential software conflict.
Should that still persist, you'll want to reach out to Apple Support: Apple Support They'll be in the best position to look into this further.
Take care.