Per https://k8s-status.toolforge.org/images/docker-registry.tools.wmflabs.org/toolforge-tcl86-sssd-web:latest/ there are two tools (giftbot & linksearch) actively using the TCL image that is using a deprecated Debian stretch base image. Debian has dropped stretch from their mirror servers making rebuilding this image problematic at best.
We should make a replacement TCL image based on a supported Debian release and let the https://toolsadmin.wikimedia.org/tools/id/giftbot and https://toolsadmin.wikimedia.org/tools/id/linksearch maintainers know about it.