I know this news is a month old, but I thought it no different at the time to Private browsing mode, and yet it is. It is specifically intended to help protect vulnerable people (for example, an abused spouse looking to find information about exiting a relationship), and where a browser profile is maybe shared with someone else, who should not see that specific websites are being visited.
Normal Private browsing is deliberately turned on before visiting a site, and leaves a complete hole in the browsing history whilst it is in use (showing someone removed browser history). The same goes for deleting recent browser history. And in both cases you must remember to perform these actions.
With Off The Record, the visited website will pop up a prompt asking if the OTR mode wants to be used (it prompts the user, and is something that qualifying websites would embed on their site for this purpose) and it only removes traces of this website’s visit. Other browser tab history continues to be recorded, leaving no suspicious gap in the browser history. This is browser specific, so obviously any other spying tools would still be operational if they record outside the browser, such as network traffic spying. I’d expect, though, this feature may be expanded further still to include some sort of automated split-tunnelling on the network, as the user action needs to be as simple-to-use as possible.
See https://www.ghacks.net/2023/05/29/first-look-at-brave-browsers-upcoming-off-the-record-feature/