print jobs making notification sounds after Linux Mint upgrade to 21

After upgrading my machine from Linux Mint 20.3 to 21, print job notifications were making "ping" sounds. 

Opened the "Sound" configuration applet, Sounds tab - turned off the sound for "Showing notifications" after scrolling down. This seems to be a newly added sound, since earlier I had turned off all sounds. (At first glance, I didn't see it, but it was visible after scrolling down.)