Create SNMP interface on host and simple SNMP item
Test item

If SNMP community is defined as a string, test succeeds

If SNMP community is defined as a user macro, test fails

tcpdump command shows that community is sent without resolving the user macro

13:24:19.884661 IP student-XX.36932 > training.lan.snmp:  C="{$SNMP_COMMUNITY}" GetRequest(28)  system.sysDescr.0
 

When fixing this, also consider that this is sensitive information, so users may be using protected macros to hide this.

SNMPv3 context name and security name was not tested, but they may have same problems.

Also, feature request ZBXNEXT-5928 is somehow related to this problem.