Populism is mostly just a pejorative label, just like "fascist" and "nazi" is. In the minds of the most, populism is politicians prioritizing pandering to the masses instead of what's true.

But on the other hand, populist label is mostly to blame on politicians of this sort, whereas labels such as fascist or nazi are given much more generously, because the populists always appeal to the broad and vague popular sentiments. Say for example covid vaccines, we had a populist but still wannabe highbrow party that always dodged the questions about them, when they were asked directly are they good or harmful, they would drift away to topics such as the right to choose because saying either of these things would lose them some votes and reputation.

In case of Italy, I feel like they are big time populists, that they won't deliver on their campaign promises, but hey, we'll see.