Lens flare and positioning
Lens flare is often controlled with a lens hood, but for wide-angle lenses the effectiveness of the lens hoods is limited. It’s also possible that a slight change of angle relative to the sun and subject can also change the presence of lens flare.
In the two pictures below the lens photo composition was slightly altered, but as you can see it makes a big difference to the existence of lens flare. Both pictures were taken seconds apart with an EF14mm f/2.8L USM lens on the full-frame EOS 5D Mark III.
If the composition change is not practical is to use your hand beyond the view of the frame to also flag off the sunlight from the lens.
Alternatively wait for the sun to move… 🙂