Issue is reproducible in RHEL 8.10 and latest madam package.

[root@rhel-8 ~]# rpm -qa |grep -i mdadm
mdadm-4.2-14.el8_10.x86_64

Steps to reproduce:

---------------------------

1.  I have created the RAID0

[root@rhel-8 ~]# mdadm -D /dev/md101 
/dev/md101:
           Version : 1.2
     Creation Time : Mon Jun 10 01:49:01 2024
        Raid Level : raid0
        Array Size : 409600 (400.00 MiB 419.43 MB)
      Raid Devices : 4
     Total Devices : 4
       Persistence : Superblock is persistent

       Update Time : Mon Jun 10 01:58:04 2024
             State : clean 
    Active Devices : 4
   Working Devices : 4
    Failed Devices : 0
     Spare Devices : 0

            Layout : unknown
        Chunk Size : 512K

Consistency Policy : none

              Name : rhel-8:101  (local to host rhel-8)
              UUID : 867ab06a:8988188d:c08503d0:8c174d1c
            Events : 24

    Number   Major   Minor   RaidDevice State
       0       8        0        0      active sync   /dev/sda
       1       8       32        1      active sync   /dev/sdc
       2       8       48        2      active sync   /dev/sdd
       4       8       64        3      active sync   /dev/sde

2. Performing the scan

[root@rhel-8 ~]# mdadm --detail --scan
ARRAY /dev/md/101 metadata=1.2 name=rhel-8:101 UUID=867ab06a:8988188d:c08503d0:8c174d1c

3.   While performing the scan no messages appeared.

      [root@rhel-8 ~]# mdadm --detail --scan
      ARRAY /dev/md/101 metadata=1.2 name=rhel-8:101 UUID=867ab06a:8988188d:c08503d0:8c174d1c

4. Once adding the entry to the /etc/mdadm.conf below warning started to print.

      [root@rhel-8 ~]# mdadm --detail --scan &> /etc/mdadm.conf

      ~~~
      mdadm: Value "rhel-8:101" cannot be set as name. Reason: Not POSIX compatible. Value ignored.
      ~~~~

NOTE: 

While running all md raid commands messages started to appeared.

      [root@rhel-8 ~]# mdadm -S /dev/md101
      mdadm: Value "rhel-8:101" cannot be set as name. Reason: Not POSIX compatible. Value ignored.
      mdadm: stopped /dev/md101

      [root@rhel-8 ~]# mdadm --assemble --scan
      mdadm: Value "rhel-8:101" cannot be set as name. Reason: Not POSIX compatible. Value ignored.
      mdadm: /dev/md/101 has been started with 4 drives.

Actual result:

-----------------

Getting below messages for each activity.

mdadm: Value "rhel-8:101" cannot be set as name. Reason: Not POSIX compatible. Value ignored.

 Expected result:

-----------------------

No need to print such message.