Hi @Ankur9981, welcome to our forum and I'm sorry to hear about this.
When the playback is stopped, is both sound and video stopped or can you for example, still hear the sound from the video? Does this occur when connected to both Wi-Fi and/or using mobile data?
I'd recommend that you reboot your phone in safe mode and play a couple of videos in the Youtube application and see if you experience the same behaviour when third party applications aren't loaded.
Let me know how it went! 
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