Version 1.9.19-2 of altos is marked for autoremoval from testing on Thu 02 Jan 2025. It depends (transitively) on gcc-riscv64-unknown-elf, affected by #1086462. You should try to prevent the removal by fixing these RC bugs.
Among the 1 debian patch
available in version 1.9.19-2 of the package,
we noticed the following issues:
1 patch
where the metadata indicates that the patch has not yet been forwarded
upstream. You should either forward the patch upstream or update the
metadata to document its real status.