Steps to reproduce:

1. API Request on event.acknowledge for an active problem event

{
    "eventids": [6811411],
    "action": 36,
    "message": 'Supressed by script'
) 

Result:

The shown "suppression" is missing in event_suppress database table. I don't know where the UI got this broken information.

Expected:
Documentation (https://www.zabbix.com/documentation/6.4/en/manual/api/reference/event/acknowledge) says parameter suppress_until is required if action contains suppressions. So I would expect that the api request fails if the parameter is missing.

But I think there is also a GUI bug. It shouldn't show a inconsistent suppression.