@strypey @ljrk Bridges are a bit different than scraping content or listening into a conversation. A bridge that bridges Activity Pub to AT/Nostr acts like any other ActivityPub instance, requesting a copy of the bridged user's profile in the same way another ActivityPub native server would. Same with Friendica (that I'm using right now to reply), it requested a copy of your post over Activity Pub, despite being native to DFRN (although, unlike Bridgy Fed/Mostr, Freindica bridges internally via plugin instead of using a dedicated standalone bridge). I'd argue that using a protocol designed for federation, on a server that defaults to federating with any instance not proactively blocked, is rather explicit permission to federate.
However, since it's just federating normally, it's easy to stop. If you block the bridges (at the user level or instance wide) they won't federate, just like any other Activity Pub instance. While I think bridges are important for the ecosystem, the beauty of something that's not centralized is that you can choose exactly what you do and don't want to interact with.