When you create a custom event use the generic build method, you have an option of assigning the custom event a primary entity type, see below. What I have seen is that if you leave this as 'None' then when a problem is created for this custom event, the problem will shows as an impacted of your environment name (see 2nd screenshot). I can't say this will occur with ALL custom events you create, just some we have created recently that are referring to a metric that we are ingesting into Dynatrace.
The problem I am facing is that for some of our custom events if we don't assign it a entity type then when the problem is created it won't be apart of any mgmt zone which means for us only the admins to dynatrace can see the problem card. This can lead to issues if a ticket is created to app teams but when clicking on the link to the problem card in dynatrace they will not have access to the problem card due to not being in their mgmt zone.
For the custom events we have app teams come to us and tell us to ingest a metric into dynatrace which we do but we have no clue what type of entity is impacted should the threshold be breached but it seems like we need to be choosing some type of entity type within the custom event to allow it to fall into a mgmt zone. Does anyone have experience with this entity type? Do you really identify the entity type that is impacted when setting these up? I imagine some times the impacted entity will not even be listed here.