Cheesecake is very hard. What's going on here?

It is estimated that there is something wrong with your formula. The basic formula of cheesecake is

Cheese, refined sugar, flour (filtered through a mesh), egg yolk.

I don't know what kind of cheese you are talking about. Generally, it tastes slippery. Use cream cheese and sometimes ricotta cheese. It tastes worse, but it's cheaper.

I'll give you the recipes made by our hotel, and you can reduce them according to your own needs.

600 grams of cheese

200 grams of refined sugar

50g flour

4 egg yolks

You can also add lemon peel, yogurt and vanilla beans to taste, so you don't need them at home.