I have read an article in which the author implies the plague of Covid-19 arose from the affliction of widows, his mother in particular. Would G-d really do that?

Firstly, we don't know God's reasoning, only that it is complex and not (!) simplistic, and how much more so regarding the most earth-shaking and far-reaching event of the last several decades. In addition, even when we try and utilize different tragedies or challenges for self- improvement, soul-searching must be done by every person regarding himself, and not regarding anyone else, as is clear from the book of Job! Please excuse me, but it seems like that author is way off base, or perhaps you didn't understand him properly.