The mediawiki_history data lake tables contain various fields that record the value of something both at the time when the edit event took place, and at snapshot time (e.g. page_namespace vs. page_namespace_latest).
It would be very useful to have the same for the property of the page being a redirect (e.g. right now in the context of T149021 where several people have been working to approximate this by parsing edit summaries, which is not entirely reliable). I.e. add a new field page_is_redirect to the existing page_is_redirect_latest.