By far the most precious resource Reddit gets from you is your insight; Reddit needs posts, especially posts with good insights on specific topics. This is the treasure trove they are sitting on and the value proposition for shareholders: a gigantic collection of long-form discussions on all kinds of niche topics that can be used for targeted and generic AI training.
So by continuing to use reddit, you are providing them with the most precious resource they seek anyway. This is why I am anxious to see a genuine alternative to reddit.
Non-affiliated publications include The Chalkdust and Quanta Magazine. There is also a rather big Mathematics discord server at https://discord.gg/math that includes graduate topics, graduate admissions etc.
I would love further recommendations from people outside the US and Europe.
There are tons of misconceptions about mathematics, but the biggest and most baffling one is: that no new mathematics is being created, that the field is "done".
The opposite is true: there are more open problems than ever, and research is frantic in mathematics with hundreds of thousands of serious new theorems being proven every year by professional mathematicians, and entirely new mathematical vistas being discovered every few years.
In fact, the pace of research is so fast that we are now creating the foundations for databases of mathematical theories and their proofs in order to better classify and preserve them.
I don't care too much about the Fediverse in itself; I was looking for an old.reddit.com-style place to share all sorts of hobbyist and technical content and have meaningful discussions on it. The interface kbin is offering suits me aesthetically better than the alternatives, so I am sticking with this site now. I like the clean but not too sparse feel, the simple threading, and the ease of browsing magazines. I would like to see comment thread collapsibility and easier navigation within a thread's comments (remove or improve pagination, for instance).
There are many limitations, but these can also be opportunities: precisely because this site is in its infancy, it has the potential to incorporate ideas from the community much faster and with more forethought than a mature, established product.
For my part, I would like to lobby slightly for native LaTeX rendering throughout kbin.social, similar to what mathstodon.xyz has. It is a somewhat niche functionality, but it would put math, physics and computer science-related magazines far ahead of corresponding subreddits in infrastructure.