@petrescatraian@noam oops, didn't notice that, but from your reply it looks like the process of filtering must be an ActivityPub feature, I think I've seen it on all Fedi apps so far...
@kudra@noam Friendica is also ActivityPub, just a different design than Mastodon/Calckey/etc. Those are all designed more toward "twitter-clone" layout and Friendica is more "facebook-clone" with the added layer of extensibility and compatibility (ie. server addons that add additional features, allow alternate ways of doing things, and even add support for connecting to other platforms like Tumblr).
"Filtering" isn't a protocol feature, it's just a server feature where it allows you to proactively hide the posts that match the filter.
In Friendica filtering is provided by an addon, the one mentioned by @petrescatraian is called NSFW (it originally only filtered NSFW and later got expanded to a simple configurable filter addon), there's also Advanced Content Filter (which is harder to use but offers more complex filters), and some specialty ones like the Language Filter (it tries to identify languages and hides posts when it's certain enough that you don't speak the language).
@noam Perhaps you can use the content filter to filter out hashtags (they will be colapsed afaik). Go to Settings > Addons > Content filter (NSFW and more) and add the terms.
It says there Use /expression/ to provide regular expressions, #tag to specfically match hashtags (case-insensitive), or regular words (case-sensitive) - so I guess it should do the trick (I haven't tested against hashtags myself so far).