I can’t see anything obvious, so I’d do a couple of things to eliminate the other possibilities,
First, preferably take the outer shell off, it’s in one of my videos. Then run a shot against the blind filter, for about 30 seconds, and check just to see there’s nothing spraying somewhere onto the steam boiler itself or some other thing causing a problem.
Observe underneath the steam boiler just in case something is leaking there that hasn’t been noticed, you’ll get a better view from the sides as well and have a good look around.
Observe the tube in the tank, see if it bubbles or noticeably steams, and if this continues after the vacuum breaker is closed. You might just be seeing the normal vapour that comes out just prior to the vacuum breaker closing.