This is a planned feature.
ActivityWatch was born out of a frustration with the privacy issues of existing life logging solutions. We feel that it’s important that some things that are exceptionally sensitive shouldn’t be logged at all. This way the cost of data breach is bounded, and the barrier to sharing your own data will hopefully become smaller.
This is expected to be almost impossible to perfect since what someone considers exceptionally sensitive might not be for someone else (due to e.g. culture and law). But the basics are easy to get right (such as not logging private browser tabs).
For the ones who believe they can adequately protect their data, they should be offered the option to disable the filter.
While we figure out how to best implement this feature, here are some options: