When placing a block using layout builder, setting the "Block background" to "Maroon - light" seems to auto-add padding equivalent to the "padding-1" attribute. When setting the block background to "Sanbar," that same padding is not there and you must manually add the "padding-1" attribute for it to match.

Example from https://mobility.dev.umn.edu/bike-center: Both blocks have only the "Block background" attribute set with no other specifications. (I have since set the "Block padding" to "Padding - 1" on the right content so it will appear the same if you visit the page.)