Filter and refresh the query on a custom widget based on dropdown values

I'm currently performing a Supabase query on the top element, which is passed into the dropdown to set some values and to the custom widget (map). The data passed to the custom widget is filtered beforehand by the values selected in the dropdown. Since it needs to have some values, I configured the dropdown to have the first three elements already selected as initial values.

I also added an action to the dropdown so that when the selected values change, it first refreshes the backend query (probably useless) and then it refreshes the whole page state. In my mind, this would also refresh the query and thus the data passed to the custom widget. Unfortunately, it doesn't work as expected.

So I'm a bit lost and don't know how to proceed. Thank you for your help!