The issue is caused by the frequency of the overhead light. If you want to avoid it, you can disable motion compensation.
Motion compensation is a feature that improves scanning performance when the barcode or phone is in motion. It does so by optimizing image capturing parameters. Under certain circumstances, motion compensation may make the images appear noisier and visually less pleasing to the eye. If image quality is a concern, disabling motion compensation may be an option. This comes at the expense of slightly slower decoding when the phone or barcode is in motion. For more static scenarios the impact on scan performance is very marginal.