The repository https://gitlab.gnome.org/GNOME/atk is archived, so I can not open an issue there asking about the current maintenance status.
Still, the current documentation page https://docs.gtk.org/atk/ shows https://gitlab.gnome.org/GNOME/at-spi2-core/ as the source repository.
The at-spi2-core repository has a folder for atk and is active in terms for commit.
So I would like to know what is the status of ATK in case consuming the latest version available. Should I use that version from at-spi2-core? Also, is the project offiacially migrate to at-spi2-core ?
ATK is a library for toolkits to provide accessibility information, which gets translated to AT-SPI interfaces, objects, and events. If you want to consume accessibility information, you should use libatspi, instead.