The problem is that there is no "the DEI". DEI stands for "Diversity, Equity, and Inclusion", and labels any of a variety of efforts to accomplish the same. Saying "The DEI is antisemitic" makes about as much sense as saying "The Accounts Payable is antisemitic" or "The Life, Liberty, and the Pursuit of Happiness is antisemitic". It's not even grammatical.

Furthermore, if you look at implementation of policies for hiring, let's say, they are highly diverse, ranging from improving outreach to groups who have a lot of strong candidates but who aren't reachable by networking very well for historical reasons, through to telling white men not to apply (and not considering them if they do) because the hiring entity needs to "increase diversity". (In the U.S., they have to be careful how they phrase this to avoid a Title VII lawsuit--this is illegal--but it still happens.) So it ranges the gamut from good business and social sense through to illegal racial discrimination.

In standard exaggerate-ridicule-destroy style, the right wing in the U.S., having previously done this with CRT and "woke", decided that they'd try the same strategy with "DEI". Thus, it become "the DEI" in their mouths.

But unlike "CRT" which is an actual viewpoint (and has natural-enough extensions to CRT-inspired views), or "woke", which is a linguistically reasonable way to label the subset of the progressive left who is big on shaming and purity tests and focuses on oppression (because their positive self-identification with being "woke" was a good way to pick them out even though they never labeled themselves), "the DEI" doesn't label any coherent thing. The woke (above definition) like DEI a lot, and Jews have power now, so you certainly will find antisemitism among the progressive left-inspired implementation of DEI efforts.

But it doesn't mean that "the DEI" is a coherent concept.

I object to your terminology because it's ill-suited for coming to an accurate understanding of anything.

Please don't get your terminology from right-wing media. It is very often intentionally designed to mislead and confuse. Thought leaders often don't even bother disguising that this is what they're trying to do.

If you want to understand the extent to which the illiberal progressive left thinks antisemitism is cool again, by all means, do so, and talk about it. It's worrying. But talk about it using terms that clarify.