Thus, it is clearly an issue from when the information is copied from Adobe Reader to the clipboard, and not an issue with Word!
Please note I use paste and match formatting in Microsoft Word, so all pasted text should match my formatting in the Word document, which is Times New Roman 12 pt and NOT in superscript. I do a lot of research-based outlines where I copy and paste a lot, and this issue is driving me mad.
As of about one year ago (perhaps with an update), every time I copy and paste from ANY PDF document using Adobe Reader DC into Word 2018-2019 (Macintosh) the resulting text is in superscript font, forcing me to manually remove the superscript.