I think Matrix is the most suitable alternative. For me at least. The Element web and desktop app is almost on level with discord and on matrix.org and other popular instances you get element call too. Plus people already use it.

This may be unpopular opinion but in my class today, even the teacher was using ai… to prepare the entire lecture. Now i believe that learning material shoult be prepared by the teacher not some ai. Honestly i see everybody using ai today to make the learning material and then the students use ai to solve assigments. The way its heading the world everybody will just kinda “represent” an ai, not even think for themselves. Like sure use ai to find information quickly or something but dont depend on it entirely.