The "other" search engine (you mean Google with Google maps/shopping recommendations etc. right?) didn't buy ads in its own system competing on a level playing field with competitors, but created new space for its own products that was inaccessible to any competitors.
In other words, Brave seems to be doing the right thing here by promoting its own products in the same way that any competing product can.
Don't assume good intentions when malice is equally likely... at least in this technology world we live in. Companies that are actually on the user's side are very rare, so you're more likely to be correct (and safe) by never giving tech companies the benefit of the doubt.
