Jeff Iannucci gives us the details:
SQL Server database ownership may seem like an insignificant concern, but choosing the wrong owner for your database can be a main contributor to security disasters like ransomware. Let’s talk a bit about how to choose an owner that doesn’t create a huge security vulnerability for you and your SQL Server instance.
(Note: this isn’t the same as being in the db_owner role, although we will look at that later in this post.)
Click through for more information. This is one of the big reasons to avoid cross-database ownership chaining or setting TRUSTWORTHY on any database. Jeff has another way of resolving this particular problem that works, but the best solution is not to use either of those features.