(difficult to confirm without coredump/backtraces).
Would a stack trace of automount or the sssd daemon be sufficient?
I tried to compile the trivial reproducer from the GitHub Issue you linked to, but I'm getting an error when I try to compile it:
# gcc sssd_tester.c -o sssd_tester -lsss_nss_idmap -lpthread -ldl
sssd_tester.c: In function ‘thread’:
sssd_tester.c:12:5: warning: implicit declaration of function ‘sss_getpwnam’; did you mean ‘getpwnam’? [-Wimplicit-function-declaration]
12 | sss_getpwnam("test", &res, buff, sizeof(buff), &errnop);
It looks like sss_getpwnam isn't defined in any of the header files in /usr/include, or I just can't find what package provides it.