Debian 12 bookworm was released on June 10th, 2023. And next day we tried to use it (in development environment). And it went unexpectedly easy, there were no problems at all. So we started to plan migration for all servers in three steps: development servers, testing (staging) servers, production servers. And today we finished migration of all production servers to Debian 12 bookworm.
From our 20 years of experience of using Debian Linux transition from bullseye to bookworm was smoothest and easiest ever.