(Note that DH key sizes smaller than 2048 have been flagged by xmpp.net for years now, and Debian and others have announced that quite some time ago.)
On tangent note: why do we even struggle to keep backward compat in XMPP then? Note that jabber.ru was last updated in 2016, so "only" 3 years ago. Yeah, that's kinda lot, but not so long in the terms of standards lifetime.
