Why is this SQL update query returning rows? I'm running the following update command

UPDATE table
SET [End] = '2018-12-17'
WHERE (ID = '5b010204-c12c-4b38-8d28-affe11684da0')


This will give the following result:
 

What can cause this on SQL server 14?
This is due to an UPDATE trigger that has a SELECT in it. Modify the trigger so that it doesn't return any rows.