Am I no longer able to add attributes to my classes as subclasses?

I have check all the resources and the latest doc says that this feature was in the project setting page, which can not be found. I am working on a free public plan, does it have to do with that? If so, I am willing to pay)

Is the issue only with me? Has this feature been disabled in the free version with the update?
Same question as https://discuss.roboflow.com/t/am-i-no-longer-able-to-add-attributes-to-my-classes-as-subclasses/5456