OPACITY MASK

It’s really not that hard, perhaps this can help:

Tool Tip Tuesday for Adobe Premiere Pro: Assign New Masks

Highlight Opacity, select tool > draw,

It took me about 15 minutes to read the entire documentation, and then click through it a couple times.

Were you trying to do this without checking the documentation? As if so, that’s a hard way to learn a drastically new tool. One which thankfully is vastly more capable and powerful than the old one.

Perhaps you should add this in the Feature Requests thread.