see https://tiddlytools.com/#TiddlyTools%2FSearch%2FSaveFilter
Just drag-and-drop this tiddler into your own TiddlyWiki. It automatically adds a “save filter” button to the $:/AdvancedSearch > Filters tab.
In that tab, clicking the button shows a popup that allows you to enter a tiddler tile, a filter definition (defaults to the current search input), and a description (also defaults to the current search input). Enter the name of a tiddler to create and press the “save filter” button. The specified tiddler will be created and tagged with “$:/tags/Filter” so it will appear in the dropdown list in $:/AdvancedSearch > Filters, ready to be selected and applied.