You are welcome Oliver!
I know it’s frustrating to deal with the WP paragraph that jumps out from no where, I do it myself time to time.
The CSS for the separator is based on the GB blocks’ ID, once you rebuild the home page, the IDs will change.
So I guess the CSS doesn’t work any more.
You can try adjust the GB container paddings to find a balance.
Have a nice weekend 🙂