ADA predates DEI by a couple decades. Lots of people, including Republicans, support the ADA and support expanding its protections.
This is a pretty standard tactic of partisans when their pet issue becomes unpopular - take something unrelated, or at best tangentially related, and pretend it's related or that that's what they've been advocating for all along.
I don't care if you support the ADA or you don't. I don't care if you support DEI or you don't. But they're different, they've never been related, and any attempt by partisans on the left to lump them together is just trying to reframe the issue as "against DEI == against the ADA" because of course everyone on the right hates disabled people right?