Moved on to matrix? Many did... and they're all realizing matrix doesn't actually work long term. There's only the synapse server and there's literally no way to trim data from the db in synapse or everything breaks. That means the db just grows and grows until it's too expensive, or too slow (re:IO), to work. That's why the matrix.org homeserver has a 55TB db. That's why many long running IRC servers gave up on running matrix bridges because it simply became too computationally/resource costly to run the simple text based server even if they loved the features.
So unfortunately Matrix is a dead end. The matrix foundation gave up control 2 years ago. Matrix is now controlled by Element.io corporation and they only care about their government hosting contracts. It's really only viable if you have a significant constant money stream to pay for the ever increasing server resources like governments/corps.
IRC persists. It is the text chat layer of the internet which is the platform. Trying to build the entire internet into your text chat platform, and storing everything, is the kind of insanity only for-profit operations do... and eventually die from. Whereas IRC being a dumb pipe with lists of IPs associated with sockets will live forever. And cheaply.
Synapse server is the only server that does the things matrix says it can do. All those others don't. Notice only two of those say 'stable' and only one, synapse, implements the full set of features. Also can't switch between them.
And your links to synapse features ("Please note that, as this feature isn't part of the Matrix specification yet, the use of m.room.retention events for per-room retention policies is to be considered as experimental.") may describe certain synapse functionality but in practice is doesn't work and the db keeps growing as does IO load. The compression thing is an attempt at mitigation because the protocol just doesn't handle it.
So unfortunately Matrix is a dead end. The matrix foundation gave up control 2 years ago. Matrix is now controlled by Element.io corporation and they only care about their government hosting contracts. It's really only viable if you have a significant constant money stream to pay for the ever increasing server resources like governments/corps.
IRC persists. It is the text chat layer of the internet which is the platform. Trying to build the entire internet into your text chat platform, and storing everything, is the kind of insanity only for-profit operations do... and eventually die from. Whereas IRC being a dumb pipe with lists of IPs associated with sockets will live forever. And cheaply.