Cookies not flattening??

Every single time I make cookies, they refuse to flatten. I have tried probably 30 different recipes and kinds of cookies, even store bought and frozen ones.

I have tried chilled dough and not chilled dough.

Hand flattening them out, banging the pan half way through, and honestly any other trick Google has had for me.

The thing is, this was NEVER an issue in the past until I moved into this house. We have a gas oven here, and I am not sure if it’s because it is gas or what.

Please please please give me any recommendations so I can make some cookies that are not still (pretty much) balls when they come back out of the oven. I just want flat cookies again!