I don’t really understand why we have two different green kind of blocks but the darker one really lacks contrast and is unreadable on mobile or on PC with sun shining.
The reason why there are two types of blocks is this:
First paragraph: when a whole new paragraph is added. The entire paragraph is marked and highlighted.
Second paragraph: when a paragraph is edited and some of the words in it are unchanged, only the new words are highlighted by adding <ins> or <del> tags around them.
The text contrast will be improved and partial / full edits will share the same style after the fix is applied.