The doesn't match any previous text operator can now be used to check if the new text change is distinct from any updates present in the change history. For instance, when monitoring a list of available jobs, if a job is added or removed intermittently then this operator can be used to suppress the noisy alerts.
ah! the firefox extension hasn’t been updated in while due to issues with mozilla store. you will need to use other browser extension of the desktop app to use this.