https://gitlab.synchro.net/main/sbbs/-/issues/884#note_6726
The changes on/around September 7, 2024 (e.g. commit cefca3c6f32c298d4a56) do seem like the likely cause:
we won't publish any messages until the connect_callback has been called and it may be called before the mqtt_startup() function reaches the point of publishing the version (and other) server topics for initial server status.
--- SBBSecho 3.23-Linux
* Origin: Vertrauen - [vert/cvs/bbs].synchro.net (1:103/705)