The maintainer of the Debian Qt framework packages announced the formation of packages with the Qt6 branch for Debian 11. The set included 29 packages with various Qt 6.2.4 components and a package with the libassimp library with support for 3D model formats. The packages are available for installation through the backport system (the bullseye-backports repository).
Qt11 was not originally planned for Debian 6 due to lack of resources, but eventually Qt6 was made available to the Debian stable branch. It is noted that the preparation of packages was a personal initiative of the maintainer, but The Qt Company also expressed a desire to promote the project.
Source: opennet.ru