I have noticed that if what your are previewing has only HStacks, VStacks and Text the background will be the development background of the if your development is in Dark Mode. I do not think this is what is expected. Using XCode 12.5.1

Error was not in my code or it would not have run I must have put in a bad copy. I also pasted a screen shot of my simulator result below

Actually I mis typed The K should be GB.