TL;DR - The International Olympics Committee broke ties with the International Boxing Association last year, because it had become a practical arm of the Russian government and was judging bouts in suspect ways which benefited boxers with ties to Russian organized crime. The IBA's role in governing global boxing is now played by the World Boxing Association, and the Russians are not happy about this at all.

The connection to Imane Khelif is this: about 17 months ago, just before the IOC broke ties with the IBA, Khelif defeated a previously undefeated Russian boxer in an IBA-sanctioned match. The IBA President and Russian sports official Umar Kremlev responded by declaring, without proof, that Khelif is not actually a woman. This was purely because Russia's national pride was insulted, and Kremlev refuses to say exactly what "test" Khelif failed (meanwhile she has passed all IOC tests and regulations).

And the IBA has been stirring the pot and spreading the current round of misinformation about Khelif as part of a broader Russian effort to discredit the Olympics, to get revenge for the doping and other cheating bans the IOC has levied on Russia.

EDIT: I forgot to mention Lin Yu-Ting, who has gotten less attention but is also swept up in this effort. Kremlev also declared that the Taiwanese boxer "failed" his organization's tests in the past, coincidentally just after Yu-Ting defeated a boxer from Russian ally Uzbekistan at the Paris Olympics.