The end of life of Debian Buster is approaching in late 2023. There will be LTS support for Buster through 2024.
As soon as Bookworm is released we should start the drive to move users off of Buster and on to Bookworm. I don't think we should start pushing people from Buster to Bullseye but we can at least start the documentation and testing process. And, in the meantime we should figure out when our actual deadline is.
https://os-deprecation.toolforge.org/
LTS support ends on June 30, 2024