debdeploy uses lsof to detect file references to deletes library file descriptors (which indicate a library that has been updated, but still is kept in memory by the dynamic linker since a process is still using it). This takes a few deci seconds on all servers, but on the Kubernetes workers is notably slow:

jmm@wikikube-worker1266:~$ time sudo lsof +c 15 -lnXd DEL
real    0m34.487s
user    0m10.342s
sys     0m24.026s

Maybe this is caused by the overlayfs mounts, needs some further investigation