The stock firmware shared on uploadrom.com helps you to re-install the Mobile Operating System on your Mobile Device. It also allows you to fix your Mobile device if it has any software error issue, IMEI error issue, Bootloop issue, and a mobile dead issue.
OPPO A53 5G Run on Android 10 & it is Powered by Mediatek MT6853 Processor. it is a dual SIM smartphone support Nano SIM cards, connectivity Option’s Include 3G 4G GPS, Wi-Fi, hotspot, bluetooth etc. the device come with 4GB of RAM and 128GB of Storage that can be expandable via SD card.

Firmware Information:
Device Name: Oppo A53 5G (PECT30/PECM30)
Type: Full OTA
SoC: MT6853
Firmware Version: PECM30_11_OTA_0100_all_yTTvpuXCnSQ1
OPPO A53 5G (PECT30/PECM30) Official OTA Updates/ Recovery Firmware:
to upgrade a working phone (first check Installed firmware version with in your Phone)
How to Install Stock Firmware on OPPO A53 5G (PECT30/PECM30):
Download Latest firmware from above
Move downloaded file to phone’s root directory
Now click on firmware and from the prompt select Install, it will start the Installation, done
Method 2:
put phone to recovery mod
Install/update from storage
locate downloaded file and click install, wait until success, done
Note: I have no idea about downgrade