Adding a username and DOB fields to a Signup page

Hello all! I'm stuck on something seemingly simple, and I'm sure there's an easy and correct solution to this. I'm trying to add two fields to my standard Signup page: Username and DOB (date of birth), so that immediately after the Auth is creating a new row in my Supabase auth.users table, it also updates the 'username' field in the newly created row in public.user_data table with the value entered in the username field (and the same thing for the DOB field). (I keep Username and DOB fields in public.user_data table instead of auth.users table, as per good practices).

The Auth is creating the user in auth.users table perfectly well. I've also set up the Supabase to create a new row in public.user_data as soon as a new user is created in auth.users , and copies the id - and this works too. I achieved this with the following function:

BEGIN
    -- Insert into user_data
    INSERT INTO public.user_data (id, created_at, balance)
    VALUES (NEW.id, now(), '0.00'::numeric);
    RETURN NEW;
END;

I've added a secondary Action to "Join" button to take the value in 'username' field's Widget State and write it into the Supabase public.user_data -- (See the screenshot). But the new row in public.user_data is not updating the 'username' and 'DOB' columns.

I'm also attaching the screenshot for public.user_data RLS.

Can anyone help, please? How do I write contents of an additional text-field (username or DOB) on the signup page into a column in supabase's public.user_data table?