Hi wm910
Thank you for your post.
Is the [Live View Display] set to [Setting Effect OFF]? When [Live View Display] is set to [Setting Effect OFF], the brightness of the shot image will not be the same as that of the displayed Live View.
If it was not set to [Setting Effect OFF], you may need to bring it to the nearest local Service Centre for further diagnosis of the issue.
For more information, you can refer to the A7II helpguide. Thanks!
Regards
Ann