No idea this was a thing, but I'm not even surprised.
Starting in version 1.54, Brave will automatically block website port scanning, a practice that a surprisingly large number of sites were found engaging in a few years ago. According to this list compiled in 2021 by a researcher who goes by the handle G666g1e, 744 websites scanned visitors’ ports, most or all without providing notice or seeking permission in advance. eBay, Chick-fil-A, Best Buy, Kroger, and Macy's were among the offending websites.
