About a month ago, Turn 10 wrote that they are "preparing Forza Motorsport for release later this year", which means a slight delay from the original plans to launch it before July 2023.
Unfortunately, we still do not have a release date or even a release month, but according to the video game influencer and insider MrMattyPlays, we can look forward to a release in October. This was revealed by himself in the podcast Defining Duke, where he said there was no other details he had to offer than precisely this little nugget.
As Starfield is being released in September, it basically leaves October and November (December is fairly unusual for major launches) as viable months for Forza Motorsport, so if Turn 10 will be able to deliver on their 2023 promise, we'd say MrMattyPlays will probably get this one right.