Roma (directed by Alfonso Cuarón and distributed by Netflix) was the first best picture nominee to not have a standard theatrical release, and there was a lot of controversy over it. Despite being the favorite that year it lost to Green Book, which is widely derided today.

In the early years of streaming the academy tried very hard to shut Netflix out of the Oscars. The company had to fight hard (including buying a theater in LA to do limited releases to satisfy their requirements) to get streaming films on equal footing. Only last year did they finally allow streaming-only releases to be considered for the awards.

Netflix distributed "Roma", and "The Green Book" is a typical 'safe' Best Picture pick.

"Roma" was the "wrong" kind of film at the time, produced by a streaming service which was then considered the mark of the beast.

"Green Book" had a "white savior" trope which is now considered non-Narrative and shunned by people who support the Current Thing.