Hi satwikZ010D,
Thanks for reaching out here in the Apple Support Communities. I understand your iPhone and battery aren't performing properly after updating to iOS 13.5.
I'm glad to help with this.
First, check to see if the health of your battery and the apps that are using it are working properly.
This article has details about how to check that, and what to do if things aren't working the way you expect:
iPhone Battery and Performance - Apple Support
Concerning the deletion of files from the Files app, please see the information below:
You can manage and delete folders or files you store in iCloud Drive from your iPhone, iPad, iPod touch, Mac, or PC. If you're a participant in someone else's shared folder, it does not count towards your iCloud storage. Learn more about folder sharing in iCloud Drive.
With iOS 11 or later, files that you delete from iCloud Drive remain in Recently Deleted for 30 days before they're removed from your device."
Manage your iCloud storage
Take Care.