Combine the graham cracker crumbs, melted butter, and sugar in a bowl until well mixed.
Press the crumb mixture into the bottom of a 9-inch springform pan, ensuring it is evenly distributed.
Beat the softened cream cheese with an electric mixer until smooth and creamy.
Add the powdered sugar and vanilla extract to the cream cheese and mix until well incorporated.
In a separate bowl, whip the heavy cream until stiff peaks form.
Gently fold the whipped cream into the cream cheese mixture until fully combined.
Gently fold in the mixed berries, being careful not to break them.
Pour the cheesecake filling over the crust in the springform pan and spread it evenly.
Cover the cheesecake with plastic wrap and refrigerate for at least 4 hours or until set.
In a small bowl, combine the topping berries with sugar and lemon juice, and let it sit for about 15 minutes.
Once the cheesecake is set, remove it from the refrigerator and top with the berry mixture before serving.