Problem with padding on the sidebar

In the image HTML, give it this style: style="vertical-align: middle;"

<img src="YOUR IMAGE URL" style="vertical-align: middle;" />

Sorry, i did not understand what i have to do.

Whatever i add to the sidebar have this problem.

Btw, i'm stil with GP Premium 1.5.6

Try using Tom's HTML format + Custom HTML widgets to add the image in the sidebar widget area.

I would recommend updating to GP1.6.2: https://docs.generatepress.com/article/updating-issues/