I understand you're looking for the (ROM). While I can’t provide direct download links to copyrighted firmware files, I can give you the exact specifications and guide you to official/safe sources to download it.
: New dynamic lock screen categories and call background options. Official Samsung Galaxy A20 SM-A205F DS Stock Rom
if you use the "CSC" file. To keep your data, use the "HOME_CSC" file instead, though a clean flash is often recommended for stability. How to Flash ROM Samsung Galaxy A20 SM-A205F Jun 17, 2019 AndroidHowTo I understand you're looking for the (ROM)