mit-scheme is marked for auto-removal from testing on 2021-11-06. It
looks like this may be due to the package dropping support for i386 in
the most recent release (11.x). Auto-removal would cascade to slib
(due to Build-Depends), and then on to other packages like scm, jacal,
and gauche.
It is possible i'm confused or have not kept with with some policy
change, and the removals will be resolved somehow (eg, ftp masters
override?). But I thought it would be worth checking with folks on
this list.
For example, maybe it would be possible to iterate (again) on the slib
Build-Depends setup.