Hello AmgXIIXXV,
We understand you're wanting to add a widget to the bottom of your Home Screen, and we'd be happy to help.
The 2x4 widget can only exist in one of 3 locations on the screen and those are the top 2 rows (1 & 2), middle 2 rows (3 & 4) or bottom 2 rows (5 & 6). When you have 3 rows of apps and try to place a 2x4 widget it cannot go at the bottom because that would try to use Row 4 & 5 which cannot be used. You can see a similar issue if you try and place the widget on Rows 2 & 3 as it bunches the top 2 rows together.
If you wish to have your widget at the very bottom, you would need at least one app on Row 4, otherwise it will always locate to the middle block. You can visit Add widgets to the iPhone Home Screen for more information on this feature.
If you'd like to leave feedback about this, you can do so here: Product Feedback - Apple
We hope this helps.
Thanks for using Apple Communities. Have a good one.