This is a bit annoying. I would like the search to be clear when I come back so that I dont have to delete the previous search first. This is more consistent with things like Alfred or Slack.
We preserve the search input (as well as the DB selection) so that you could explore multiple results one-by-one when you are not certain which one is the one
See Search Panel, certainty #2.
To start a completely new search, we recommend opening a new panel (ex. Ctrl+Shift+>) or clearing the desk with Ctrl+Shift+K.