Is a hardware or software issue?

iPhone 8 have problems with the cameras in apps.

It happens on off. Most of the time the front camera works fine, but the back camera is sometimes blurry, black or works shortly.

Every thing else works as normal. Battery is at 89% and other applications is doing well. It has been going on for over three months.

The iPhone has no damage on the cameras and I tried many options.

Right now, I am considering reparation on the iPhone. I had tried hard reset, rebooting and turned it off to cool down. Plus looking at third party, if that should causes the problems. My iPhone is also updated and is about three years old. I bought it as new.