I’m not able to consistently reproduce this on try, so I’m not sure. I created a topic with a 28 character word in the title (limit is 30), submitted, waited 5 minutes, lowered the site setting to a 20 character limit, then changed the category without error (which should have failed?). Attempting to add to the title gave the expected Title seems unclear, is it a complete sentence? error. If I modified the title and changed the category I received a 422 error, but this is not consistent with what I first saw.