Uber Eats faces lawsuits over free delivery from Black-owned restaurants

Uber ditching delivery fees for category X

can be also read as:

Uber charging delivery fees for those not belonging to category X

The net effect is anyway that a same meal, with the same list price will arrive at your home with - say - 20% different (+ or -) cost due uniquely to the race of who prepared it.

Sure it is a form of discrimination, whether it is "good" and/or made in "good will" and for a "good cause" should be irrelevant for the Law, of course it has to be seen.

Had they provided an option to donate money to a cause that happened to distribute it to black restaurants, they may have been able to circumvent this. What they do with the money they earned is their business.