Hi there LeafyAnimations,
You can learn more about how the 'System' and 'Other' content categories use space on your device as well as how to free up storage using this article: How to check the storage on your iPhone and iPad
We'd also recommend ensuring your iPhone is fully updated as this can resolve issues like this. These steps from Update your iPhone or iPad show how to back up and update:
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.
If this continues after updating looking over that article, reach out to Apple Support next. They would be the best equipped to look into this issue with you further. Contact them here: Get Support
Cheers!