Why the ACL permission bits are modifying the file mode permission bits ?

Issue

In the following scenario, the setfacl always changes the file mode permission bits for directory's group from 700 to 750 i.e. from rwx-- to rwx-rx-. Would it be possible to change the folder's file mode permission bits to 700 but keep the access right for another user testu02 where testu01, testu02, testu03 users belong to the same group testg ?

$ mkdir test
$ chmod 700 test
$ chown testu01:testg test
$ ls -l test -d
drwx------ 2 testu01 testg 4096 Jun  4 10:08 test

$ su testu01 -c "ls -l /tmp/test"
total 0
$ su testu02 -c "ls -l /tmp/test"
ls: cannot open directory /tmp/test: Permission denied
$ su testu03 -c "ls -l /tmp/test"
ls: cannot open directory /tmp/test: Permission denied

$ setfacl -m u:testu02:r-x test
$ getfacl test
# file: test
# owner: testu01
# group: testg
user::rwx
user:testu02:r-x
group::---
mask::r-x
other::---

$ ls -ld test
drwxr-x---+ 2 testu01 testg 4096 Jun  4 10:08 test
$ su testu03 -c "ls -l /tmp/test"
ls: cannot open directory /tmp/test: Permission denied
$ su testu02 -c "ls -l /tmp/test"
total 0
$ chmod 700 test
$ ls -ld test
drwx------+ 2 testu01 testg 4096 Jun  4 10:08 test
$ su testu02 -c "ls -l /tmp/test"
ls: cannot open directory /tmp/test: Permission denied