For example, consider http://www.vim.org, which hosts the text editor Vim. The author, Bram Moolenaar, makes this editor freely-available, and asks that any donations be directed to ICCF Holand, a charity that serves the Kibaale Children's Center in Uganda.
The Brave browser, as it stands now, inserts itself in the middle of this established reader/contributor relationship and now claims that it'll take your donations and administer them on Bram's behalf. The user who falls for this scheme then sees what appears to be _additional_ requests for donations (the _actual_ request). _At a minimum_, this inserted message sows confusion where there once was none. In the worst case, money that would have gone to the ICCF is now held in escrow by Brave, and may or may not be delivered, and if so, will go to Bram directly rather than to the charity he hopes to support.
This is just one example of how the browser intercepting and modifying what you see is a truly bad design (intentional or not).