If your appliance does not make steam anymore or less, it may be scaled. First, follow the classic procedure for emptying the unit:

If this still does not work, you can use white vinegar.
You just have to put it directly in the tank (1/3 white vinegar, 2/3 water), then start the device (making sure not to put any clothes near the diffusion head), and let the tank empty.
The procedure with the vinegar is identical for the home, pro and nomad ranges.