black ComboBox DropDown if using widget scaling 2 on Linux (KDE)

[sherpya]

I'm using KDE on X11, the combobox dropdown is full black when values count > 468 if the scaling is 2 (it happens exactly with widget scaling > 1.8)
here the sample and both screnshots:

import customtkinter as ctk


class ComboTest(ctk.CTkFrame):
    def __init__(self, master, on_change=None, **kwargs):
        super().__init__(master, **kwargs)
        self.on_change = on_change
        self.values = [f'Value #{n}' for n in range(469)]
        self.font_var = ctk.StringVar(value=self.values[0])
        self.font_menu = ctk.CTkComboBox(
            self,
            values=self.values,
            variable=self.font_var,
            width=250
        )
        self.font_menu.grid(row=0, column=0, padx=5, pady=5)


if __name__ == '__main__':
    app = ctk.CTk()
    app.title('Combo Test')
    app.geometry('300x100')
    selector = ComboTest(app, on_change=lambda f: print(f))
    selector.pack(padx=20, pady=20, fill='x')

    ctk.set_widget_scaling(2)
    ctk.set_window_scaling(2)

    app.mainloop()