Steps reproduced on 7.0.13:

1. The event is opened.

2. Validate existing tags in the event.

3. Validate tags inherited from the template in the event trigger.

4. additional information

1) Which Zabbix version are you using ?

11.0.13
2) Is there a message "item_rtdata entry unexpectedly is present for item" in server logs ?

No messages "item_rtdata entry unexpectedly is present for item" in server logs

3) Does the following query return anything ?

Result:
See screenshot event

Trigger Details with Tags Inherited

Expected:
That the event inherits the template tags