There is a web dashboard bug in when you filter your maps (on a keyword or partial text match), then use the Select All, then Delete… Maps that are “hidden” (did not match your filter) are also selected in the background, and deleted unintentionally.
I just finished uploading a big data set that was starting to process and then wanted to delete some “bad” maps that were never flown, and I unintentionally deleted my valid map.