This search is looking at events. ObjectIds are included in a particular "event" and an "event" can have many objectIds, all of which trigger executions. The result set consists of all executions that kicked off with the event that included the "Object ID" that was searched for. Therefore each record in the result set will have the same trigger.eventId which can be tied back to the Event logs.
The Formula Execution search form is hitting our platform api at:
And the docs for that endpoint explains how the objectId parameter filters the results:
"The object ID, which will return all executions that were triggered by a specific object."