Comfort lock, Passat 3B, year 1998

Hallo zusammen, when I open the doors of my Passat 3B, 1998, using the door lock and holding the key in the unlocked position, and vice versa, all the windows (except the front and rear windshields, haha...) open and close. What's not working anymore is that when I press the window button for the driver's window to open, I have to hold the button down. Previously, I only needed to tap the button and the window would go all the way down. What could be the cause? And one more question? Do the buttons also need to be pressed for an extended period of time?
Best regards,
Kradmelder

[Translating...]Fahr das Fenster ganz herunter und halte den Knopf gedrückt
bis ein Klacken aus der Tür zu höhren ist. Dann das Fenster wieder hoch fahren und Knopf festhalten bis zum Klick. Diese Prozedur für jedes Fenster wiederholen.