Is this a bug with custom forms?

Hi all!

I don't know if this is a bug, or design behaviour; can anyone tell me?

Let's say I have an incident which is in the wrong category... when I change it to the right one using the inline edit on the individual incident screen, it pops up a "Update Custom Form" screen on which I have to click "Update" to validate the change I already made! It does NOT do this if I change the category in the incident list.

I believe I have disabled all dynamic forms rules and custom forms which are associated with the category and subcategory field.