The image is being reprojected on-the-fly to the map Coordinate Reference System (CRS), which is not the same as the image CRS.
You can change the map CRS with the Project ~> Properties ~> CRS setting.
If you tick on No projection, all data will be displayed without being reprojected.
Or you can get the raster layer CRS by selecting it and checking the Layer ~> Layer Properties ~> Information ~> CRS data. Then you can set the same CRS to the map (project).