In case of using Zabbix in different countries with different languages, many of them are using multibyte symbols with their native characters. Option "Tag name" - "Shorten" into the "Monitoring" - "Problems" does not support multibyte characters that causes, for example, tag name "Дежурным" being truncated to "Д�" (2 bytes is a symbol and 1 byte is half of a multi-byte symbol) that made the tag name visually broken. Changing truncating function from "substr" to "mb_substr" into a PHP backend will solve the problem.

Here is pathces for currently supported Zabbix versions.