Hello, how are you? I bought my marax a few days ago and I'm seeing a behavior that I think is not normal. When I take a shot, the water comes out very hot and with bubbles.
It is my first espresso machine but from what I see in the videos and from the course I take it seems to me that it is not normal.

When the machine is idle on, is better you keep the group lever completely down, not in middle position.

Good eyes, Giampiero. I was only studying the showerface.

So it looks like the brew boiler is too hot, if only looking at the showerface, but it could be that the brew boiler is being allowed to boil out its water if you're not keeping the brew valve closed at idle (lever down as Giampiero spotted), or potentially a leakage over the expansion valve.

Hi, Mara X is an HX machine, and it doesn't have a separate brew boiler AFAIK.
So bubbles at the beginning of the shot after some period of idling is expected behavior, And it still requires a cooling flush before making a shot. Here is a good explanation:

The MaraX has a switch to go between classic HX behavior (which requires flushing) and is unique self-regulating mode. If in the self-regulating mode, you should have stable brew temperature without flushing. Check your manual for the location and switch labels.

Edit: In this Extended Guide it is described in Section 11. If you have the manual that came with your machine, I'd consult that to confirm.