Yes—this is expected when you brighten underexposed shadow areas, especially at higher ISO. The artifact is chrominance noise (color noise), and pushing exposure in post makes it much more visible.

In dark parts of the image, the camera captured very little signal. When Lightroom boosts exposure, it also boosts the noise that was already present, so colored speckles or band-like patches can appear. That does not by itself suggest a faulty sensor.

To reduce it, try to expose more accurately in-camera when possible, avoid heavy shadow lifting, and use Lightroom’s color noise reduction if needed.