Actually our Zabbix version is 5.0.12, but I have not found it on a list of "Affected Version/s" field.

We have an issue with Zabbix Server 5.0.12 and underlying PostgreSQL-13.3
There come slow queries (more than 10 min, actually up to 1 hour) doing stuff like:

SELECT h.* FROM history h WHERE (h.itemid IN (<some_list_of_item_ids>) OR h.itemid IN (<some__another_list_of_item_ids>) OR h.itemid IN ...

... and so on.

Coressponding item ids are Linux CPU metrics from Zabbix native Template "OS Linux".
Fresh investigating showed 50 simultaneous backends (except for parallel workers) with that query.
Such events cause Zabbix Server performance decrease and sometimes Zabbix Server fails during it.

After previous problem we have started a topic on forum (https://www.zabbix.com/forum/zabbix-troubleshooting-and-problems/492899-long-queries-in-underlying-postgresql-13-3) with no answer unfortunately.