you have a big problem with ur images mate
To improve computer version just install wp smush it and pass it to all your images you will get better score, the image size on computer is well because google advise you to do a “losslessly compressing ” only
To improve your score on mobile is other thing, google advises you to “compressing and resizing” the images, so the images on your mobile version are big and they are resized to fit the screen, find a way to serve smaller images on mobile, after doing that compress them with smush it.
If u achieve to do that your score will increase a lot
