No, it's weird. I didn't upvote all of those posts. (I took another look at the link). They'd probably used my posting key through a third-party app.

Could tell me if my account is still upvoting those posts? If so, how can I proceed with stopping these upvotes?

Edit: I remember going to steemworld(.)org to remove all the third-party apps from my account. Some months ago. So I am optimistic that those questionable upvotes had stopped ever since.