debian/sympa.postinst for the Debian Sympa package before 6.2.40~dfsg-7 uses mode 4755 for sympa_newaliases-wrapper, whereas the intended permissions are mode 4750 (for access by the sympa group)
https://www.debian.org/security/2020/dsa-4818
https://salsa.debian.org/sympa-team/sympa/-/merge_requests/1