def update_dropdowns(self, df):
        # Update dropdown menus with unique areas from the DataFrame
        self.areas = ["none"]
        self.areas.extend( df[df.columns[1]].unique())
        self.gui_components['area_dropdown_1'].clear()
        self.gui_components['area_dropdown_2'].clear()
        self.gui_components['area_dropdown_3'].clear()
        print("mitte update dropdown")
        for area in self.areas:
            print("start for loop")
            self.gui_components['area_dropdown_1'].addItem(area)
            print("after_1")
            self.gui_components['area_dropdown_2'].addItem(area)
            print("after_2")
            self.gui_components['area_dropdown_3'].addItem(area)
            print("after_3")

All area dropdowns are created in exactly the same way. When this funciton is called the following is printed:
enter image description here

as you see it is called a lot but never prints the last statement and throws a maximum recursion depth error. Because of this i assumed that the error was in the last self.gui_components call.

Therefore I commented it out and it worked fully exept the one combo box was missing in the gui. But no errors. Weirdly all following codes work:

def update_dropdowns(self, df):
        # Update dropdown menus with unique areas from the DataFrame
        self.areas = ["none"]
        self.areas.extend( df[df.columns[1]].unique())
        self.gui_components['area_dropdown_1'].clear()
        self.gui_components['area_dropdown_2'].clear()
        self.gui_components['area_dropdown_3'].clear()
        print("mitte update dropdown")
        for area in self.areas:
            print("start for loop")
            self.gui_components['area_dropdown_1'].addItem(area)
            print("after_1")
            self.gui_components['area_dropdown_2'].addItem(area)
            print("after_2")
            #self.gui_components['area_dropdown_3'].addItem(area)
            print("after_3")

def update_dropdowns(self, df):
        # Update dropdown menus with unique areas from the DataFrame
        self.areas = ["none"]
        self.areas.extend( df[df.columns[1]].unique())
        self.gui_components['area_dropdown_1'].clear()
        self.gui_components['area_dropdown_2'].clear()
        self.gui_components['area_dropdown_3'].clear()
        print("mitte update dropdown")
        for area in self.areas:
            print("start for loop")
            self.gui_components['area_dropdown_1'].addItem(area)
            print("after_1")
            #self.gui_components['area_dropdown_2'].addItem(area)
            print("after_2")
            self.gui_components['area_dropdown_3'].addItem(area)
            print("after_3")

def update_dropdowns(self, df):
        # Update dropdown menus with unique areas from the DataFrame
        self.areas = ["none"]
        self.areas.extend( df[df.columns[1]].unique())
        self.gui_components['area_dropdown_1'].clear()
        self.gui_components['area_dropdown_2'].clear()
        self.gui_components['area_dropdown_3'].clear()
        print("mitte update dropdown")
        for area in self.areas:
            print("start for loop")
            #self.gui_components['area_dropdown_1'].addItem(area)
            print("after_1")
            self.gui_components['area_dropdown_2'].addItem(area)
            print("after_2")
            self.gui_components['area_dropdown_3'].addItem(area)
            print("after_3")

with this output:
enter image description here

but in completion it does not work. I also tried this:

def update_dropdowns(self, df):
        # Update dropdown menus with unique areas from the DataFrame
        self.areas = ["none"]
        self.areas.extend( df[df.columns[1]].unique())
        self.gui_components['area_dropdown_1'].clear()
        self.gui_components['area_dropdown_2'].clear()
        self.gui_components['area_dropdown_3'].clear()
        print("mitte update dropdown")
        for area in self.areas:
            print("start for loop")
            self.gui_components['area_dropdown_1'].addItem(area)
            print("after_1")
            self.gui_components['area_dropdown_2'].addItem(area)
            print("after_2")
            #self.gui_components['area_dropdown_3'].addItem(area)
            print("after_3")
        self.update_last_dropdown(self.areas)


        
    def update_last_dropdown(self,areas):
        for area in areas:
            self.gui_components['area_dropdown_3'].addItem(area)

This throws the same error as in the start.