zabbix mysql database is required to have utf8 encoding and utf8_bin collation (for the database to be case sensitive).
while partially documented in
ZBX-6323, it was still quite invisible for many users as all the relevant upgrade notes were not updated (and even if they were, users would still miscreate the db).
many users report all kinds of issues :
the time spent on such cases could be saved if the incorrect database config coud be detected and communicated to the user.
it is suggested that server & proxy check encoding & collation upon startup for all tables; if any are found to be wrong, report that as a warning in the logfile (but still start up to give the user some breathing room)