The other option though not the correct way would be to check in when you get those reminders just to keep on schedule if you won’t be gone for long periods 🤷♂️
Not up to them to cancel your extension. It's your responsibility.
An expired work permit is not a canceled work permit. You might want to check on that status.
A fellow teacher changed schools and his previous school didn't for some reason cancel his WP. The new school was unable to get him a WP until he traveled back to the old school in a different province to take care of the matter.
It's not really an issue if you're going home or to another country but if you want to continue teaching legally in Thailand you need to get things squared away. Thailand doesn't help those that don't help themselves.