I know this problem only too well, which is very annoying. I also have this problem with my "Bialetti". Now I put in less powder and less water so that I can enjoy my 2 espressos (small cups) without losing water. If this does not work, send it back to Galaxus. Because this should not and must not be the case. The hot water is also a source of danger! Greetings k.hü

It's best to watch videos on this, including one by James Hoffmann. He explains things exactly. If it thunders out of the top, you've left the pot on too long.

As far as I know, you should only fill the water up to below the valve.
I fill the powder up to the upper edge of the filter and press it lightly.
Then I screw the jug shut until I feel the resistance of the rubber seal and tighten it a little more (a little jerk).
In mine, water or coffee only comes out between the lower and upper parts if I haven't tightened it enough or the seal is old.
The coffee only sprays out of the lid if I have filled it with too much water. Then the valve also whistles sometimes.
The pot could also be defective if all else fails...