XMPP: When a 25-Year-Old Protocol Becomes Strategic Again
process-one.net
process-one.net
It's everything but mature. XMPP is a DIY flatpack plastic model kit that requires a lot of experience with super glue and paint to correctly build. As with all open source things, it is nowhere near as mature and safe as a simple Lego kit that anyone can buy and assemble in an hour.
At the time I was looking into it closely, there were issues with XML, like with the starttls messing the original document, there were issues with XML validation (for xml namespaces I think?), and other minors arrangements with the XML spec such that using a normal pull parsing lib was not enough to solve all problems. But it was quite a long time ago (10+ years), possibly that have been solved for a while.
[1] https://codeberg.org/inputmice/Conversations#xmpp-features