The original meaning is opposing the people with the elite, but it has slid to include the demagogy (telling people what they want to hear rather than the truth) to please the targeted people.
The definition from the comment above includes left wing and right wing populist main demagogy subjects. Although there may be a difference between European and American political culture on this, I am not certain.
It is not specific to right wing, left leaning newspapers use it this way too, it has become normal politics vocabulary. I think that's left leaning: https://jacobin.com/2024/03/left-populists-working-class-voters.