For me it's outright theft of ad revenue and I will never support its use. I'm not up to date on all this but I would support Google suing Brave over this.
Discussion
A user has to make a decision to use brave and opt-in to ads, which redirects revenue - I see no legal problem with what brave has done.
There are lots of ethical concerns about brave’s business model, brave’s token usage, and also the data usage by ads deployed on most websites, which are by default not opt-in.