Zoomed-in and dynamic range compressed profile stack of 1000 continuous rotations (pulse numbers 150 to 1150) of Q-mode emission taken from the second observation on 2023-04-24, as shown in Fig. 3 right panel. The bottom panels show the same parameters as in Fig. 3. We separately display the MP (left) and IP phase range (right). A longitude-stationary amplitude modulation in the leading profile sub-component of the MP is clearly visible. The IP’s intensity is modulated with the same period and synchronously with the MP’s leading profile component.