This problem started in my device after the Black startup screen as been fixed. The new Minecraft startup screen with the new Mojang logo gets cut from left and right side of the screen like it’s been zoomed a bit. It doesn’t bother the gameplay but still, it is like a missing peice of a puzzle. Note that my tablet's (Samsung Tab 3v 7.0") screen is correctly in 16:9 aspect ratio and it only happens to my device. (I also tested on other devices)
I thought I wouldn’t add this but, the startup screen rarely becomes black again. Sorry I couldn’t add it's photo.

Here is the photo of the incorrect aspect ratio of new Minecraft startup screen and the video proof that I didn’t crop the image and I'm not wasting your time.