"extra" padding below / included in text box on blog posts.

I am trying to add a text box with a dark background on the bottom of certain pages  for a clients site. They need to appear on a "blog page" and also a regular "blank" page. With all the settings for the content the same, the block on the 'blog' page (B) has some extra space below (see pictures - I also included one with the background inset (C) to show the extra black below it.

Any ideas / help  appreciated! I would just like them to be consistent like the 'blank' page (A)

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