Package: bugs.debian.org Severity: serious https://bugs.debian.org/release-critical/ says "2619 release-critical bugs were closed and NONE were opened."
Looking at individual bugs, it seems the BTS no longer knows packages and versions in stable/testing/unstable/experimental (oldstable is fine). https://bugs.debian.org/release-critical/graph-month.png The recent downwards bump in the red line was the Packages.gz change affecting unstable, but that had already recovered (and went higher than before since the Packages.xz fix also fixed version tracking for experimental that was broken for half a year). But something (different?) broke between 6:00 UTC and 12:00 UTC today, and in addition to unstable and experimental is also affects stable and testing.