kubuntu – Maintain aspect ratio while rotating the video through MPV media player

I am currently using MPV media player in Kubuntu 21.04. To rotate the video by keyboard, I edited nano ~/.config/mpv/input.conf file and added:

r cycle_values video-rotate 90 180 270 0

Now whenever I play a video by MPV and press r. It will rotate video.
I am playing a video (say demo.mp4). Now I press r then It is rotating my video by 90 degree as given in below image.

enter image description here

But It changes the aspect ratio after rotating by some degree.
You can see the default image of this video without any rotation at this time is given below –

enter image description here

There was no issue when I was using MPV before in elementary OS.
This issue comes when I start using Kubuntu.

How can I solve this problem?