Currently, masking of macros is in development in https://support.zabbix.com/browse/ZBXNEXT-2957 and while this is a usefull feature it is not enough for some use cases.
For example, user media contains "Send to" field that can contain email (for email media type) or some token / endpoint for webhook media type. Both email and tokens / endpoints could contain sensitive information that should not be exposed to other users of Zabbix Frontend:
Proposition is to allow to hide value of "Send to" field from UI. Then we can have single webhook script and multiple user tokens defined in user media without the leak of such tokens. The same problem is there for SMS message type where phone number is exposed.
Additionally, I propose to introduce some unified UI control that will be used to define such "secret" fields in future: