These artifacts are lens flare and ghosting. They happen when a strong light source, especially the sun, hits the lens directly or from just outside the frame and reflects between lens elements. That can show up as a washed-out bright patch, reduced contrast, or a series of circles/rings.

In your second image, the circles are likely ghost reflections made worse by a front UV filter. Filters can add extra reflective surfaces, so light can bounce between the filter and the lens and create those circular shapes.

To reduce it:

• use a lens hood when the light source is outside the frame
• recompose slightly so the sun is in a different position
• shade the lens with your hand if needed
• remove the UV filter if flare is a problem
• keep the front glass/filter clean

So the lens is not necessarily faulty; this is a common optical effect in strong light.