This means your KG (Knowledge Guard) state is "Checking." You must wait 7 days with the phone connected to the internet, or flash the combination firmware to reset the KG status.
The A20 launched with One UI 1.1 (Android 9) and received updates to One UI 2.0 and 3.1 (Android 10/11). Official Samsung Galaxy A20 SM-A205F DS Stock Rom
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Once you have the official firmware running, you might want to root. Here is the safe method: This means your KG (Knowledge Guard) state is "Checking