After factory default - still asking for PIN code.

My A71 wasn't in use for a long time and we forgot the PIN code. as I learnt, the only solution was to reset the phone to it's factory default, which I did. yet, while setting up the phone after that and during the process of setting up - I've got a screen asking for PIN code, telling me that default factory settings was preformed on my phone. asking for the PIN code to unlock it. First, how can I solve it? if I had remembered the PIN code, I wouldn't needed this thing on first place and a second question, if it was set back to factory defaults, why does it asking for PIN code?