Guys if you also facing this battery problem you can comment.

[Mayank_01]

After last update in Galaxy M21 Battery draining too much. I have used my phone only three and half hour it consumed 53% of battery and device freeze, restart automatically.  Please samsung see to it. I'm not happy with you. 

Edit:- It has overheating issue also.

[Chanakya_Reddy]

Ok
You can take backup of your important data. Factory reset solves any bugs if have.
https://youtu.be/IhOVhLRSSDY
See this video for factory reset guide.
I am not forcing you. It is my suggestion.

[Mayank_01]

Ok

[CS_member7]

Dear Samsung Member,

Greetings from Samsung Customer Support!

We acknowledge your query and apologize for the same. To resolve your device battery drain issue please visit this link: https://www.samsung.com/in/support/mobile-devices/samsung-mobile-battery-drain-issue/  

To resolve your device hanging issue please visit this link: https://www.samsung.com/in/support/mobile-devices/how-to-restart-the-device-when-freezed-or-hanged/ 

In case the issue still occurs. Please register your concern in Samsung Members Application (Open Samsung Members Application > Get help > Send Feedback > Error report/Ask questions).

Thank you for writing to Samsung. 

Warm Regards,  
Samsung Customer Support