Certain keywords are exiting my action.
First of all, I'm aware that there are built-in/system intents (docs). I know that there are conversation exit keywords that trigger actions.intent.CANCEL and exit the action/conversation (eg. "exit", "cancel", "stop". See docs).
However, I cannot find any documentation referencing the keywords that are exiting my action (and any new one I create).
Keywords like "thank you", "help", "call center", consistently exit my action and submit the user query globally to Google Assistant. For example, inputting "thank you" during a conversation in my action will exit (ie. " has left the conversation") and Google Assistant will answer me with something like "That's what I was built for!". Testing in the simulator shows this exit as an invocation error (See screenshot_1), testing with Google Assistant on mobile shows the exit from action and answer from GA (See screenshot_2).
Why is this happening instead of a fallback intent?