To move assets between versions of the Aave protocol (i.e., v2 and v3 ), you will need to withdraw your funds from v2 and supply your funds into v3. For example, if you supply funds in ETH v2 and change to ETH v3, you will not see your balance from ETH V2 reflected in ETH v3 until you withdraw your funds from ETH v2 into your wallet, change markets from v2 to v3, and supply your assets to ETH v3;

Keep in mind that moving funds from Aave v2 to v3 will cost you gas fees.