Did Cats have any screenings before it's actual release is question we all want to know
Screenings in general I don't think make or break a film for a studio these days, just good or bad for publicity is all.
The majority of Millennials and especially Gen Z think they know how everything works in the world today. They think if you bully enough you can get results and if they were to break the law, such as leaking a film out, they can do so without dealing with any consequences as well.
DC sells better than Looney Tunes apparently. The pandemic caused all 2020's release dates to be pushed back later and later in the same year with many ultimately being pushed into 2021.
WB owns Looney Tunes though, they have final say on all completed projects; they took the tax write off as they know the movie sucks and is not worth spending more money marketing it.