Create new item, and a trigger on that item. Make sure trigger goes into problem state and navigate to Monitoring -> Problems to confirm.

Once confirmed, disable this trigger, navigate back to Monitoring -> Problems and confirm the trigger is not in the problem state(==hidden) anymore on this view

Now, if you navigate to configuration -> hosts -> {host} -> triggers, you will see the trigger is still in the problem state. It is still in the problem state in the DB and api call problem.get will still pick it up.

According to the docs:

A trigger may have the following status:

If trigger is disabled (or corresponding item for that matters) we can never determine something happened and the PROBLEM state is misleading.

I think this behaviour should be changed. If host, item or trigger is disabled the state should be reset to normal (or unknown?).