Hi Nickhitz,
We'd like to thank you for giving us the chance to assist you with the performance of your Apple devices, rest assured that we’ll do our best to assist you.
we recommend updating the device if you haven’t. While it isn't inherently assured that an update will resolve the issue, updating can help isolate potential software issues. Kindly secure a backup and install the latest supported iOS and watchOS on your devices
How to back up your iPhone, iPad, and iPod touch
Update your iPhone, iPad, or iPod touch
Update your Apple Watch
Also, have you had the chance to check if the available storage of your iPhone is extremely low? You can find this detail under Settings > General > About.
Finally, have you had the chance to check the Battery Health of your iPhone? You can use the article below to learn more how Battery Health may affect the device's performance.
Battery and Performance
Take care!