Hello 252884,
I recommend resetting your video settings on your camera and making sure the lenses on the back are clean. Take a look at two lenses on the inn a well-lit area, one of the lenses’ could be cracked.
If you flip to the front-facing camera, is that also blurry?
Settings > General > About > software version. Follow these steps to determine the version of IOS you are running, and make sure it is fully up to date. 15.6 is the current version.