Debian (and derivs) have similar tooling (and the vast majority of rust packages are tracked in a monorepo https://salsa.debian.org/rust-team/debcargo-conf).

My point was "some of the upstream versions were older than Debian's" which means the "Debian is behind, Debian is slow" is not true in the case. That usually only happens where an upstream is either very conservative with bumping versions, or where upstream is under-maintained, neither which at first glance seem to be true of becache-fs.