In the new version, after I set a custom icon (SVG) in the button element, the icon is out of normal size after the second change. The SVG icon size in the code is 24px. This problem does not exist in other elements. The problem is solved after reloading the builder.
I can replicate the problem and have added it to the internal bug tracker. The attribute values are duplicated when the icon is changed. We will update this thread as soon as it is fixed.