Periodically, problems are generated with some incorrect headers when using the {ITEM.VALUE} macro.
The problem is floating, when creating a new item and trigger, it cannot be reproduced. The problem occurs after some time has elapsed.
The screenshots show that the event was created on 2023-06-14 16:05:19,
the error text at that moment was 'response code "503" did not match any of the required status codes "200"'
the previous value was recorded in the text of the problem, it is also visible in the notification screenshots.
It works out differently for different types of notifications, where the text from {TRIGGER.NAME} everything works correctly, where it is used {EVENT.NAME} wrong.