There have been a number of reports arguing that anti-Semitism on Twitter increased significantly after Elon Musk purchased the social medial network. Here is one example:
https://www.washingtonpost.com/politics/2023/03/20/antisemitic-tweets-soared-twitter-after-musk-took-over-study-finds/
Note that Musk is suing the organization that produced the report.
Understandably, the ADL has been concerned about such an increase and attempting to work with Twitter/X to combat it. In late August, X CEO Linda Yaccarino met with ADL CEO Jonathan Greenblatt to discuss the issue. Both Yaccarino and Greenblatt praised the meeting:
This inspired a number of the Nazis that Musk has allowed back on Twitter to start complaining to Musk. Musk, who seems to be influenced by the worst corners of X/Twitter, bought their argument and began a series of tweets criticizing the ADL. Musk continually escalated his tweets t the point that he actually accused the ADL of trying to kill X/Twitter:
This eventually reached the point of Musk threatening to sue the ADL for defamation:
This is quite an extraordinary situation and shows how the Overton window has slide on the topic of anti-Semitism. If you will remember, early in the Musk era of Twitter, Kanye West was suspended from Twitter because of anti-Semitism. West was recently allowed back on the platform. In the meantime, Musk has been platforming and promoting Nazis. Now he is arguably engaging in anti-Semitism himself, scapegoating Jews for his own failures.