In what sequence are ACL rights checked in linux via Samba?

Question

linux

There is a shared folder. getfacl /home/pub/123

# file: home/pub/123
# owner: samba
# group: samba
user::rwx
group::r-x
group:PUB_RW:rwx
mask::rwx
other::r-x
default:user::rwx
default:group::rwx
default:group:PUB_RW:rwx
default:mask::rwx
default:other::rwx

the ftp user is a member of the PUB_RW group,
in samba:

guest account = ftp
map to guest = Bad User
security = user

however, nothing can be written until you explicitly give permission to the ftp user, why is that?
from the terminal, from the names of another user who is also a member of this group, files are created