it seems that when you put a vertical flexbox into a grid field and you want that the flex items have a margin of 8px top and bottom that you can’t use the technique of giving the wrapper -8px top and bottom. It will only affect the top margin but won’t affect the bottom margin.
It does look like you removed flexbox though. I did some more testing and it doesn’t look like grid affects this. If you have a plain div block and a collection list inside and you use the 8px of margin on the collection items, the -8px doesn’t undo this effect:
I use flex on the “Collection List” because I want them to take the whole space vertically. The 8px margin on top and bottom of the collection item itself is for giving them spacing to each other. By doing this I also ad 8px of spacing to the top and bottom of the list and align this I use minus 8px top- and bottom-margin on the “Collection List”.
In my example above its working perfectly, so I think it has something to do with the grid.
That said, you may have made some changes to make sure it looks how you want it. This makes it a bit tricky for us to debug though as I’m unable to recreate the same set up.
If you’d like us to investigate further, can you please create an additional page in this project that shows the same layout with the issue you are referring to? Or you can duplicate this project and change the layout to show the error and we can debug from there.