To describe what I'm talking about just a bit more, I've got 4 accepted answers today, so I'm able to receive 260 reputation points today: 60 from accepted answers and 200 from upvotes. However, because of these -10 points I earned only 250 reputation, no matter how many more upvotes I receive.
The loss of reputation affects the rep cap of the day the upvote was given, not on the day the upvote was removed.
If you had exceeded the rep cap by more than 10 rep on the day you got the upvote from the now removed user then you would not have lost any rep; the other rep from that day would have compensated for the lost rep.
The fact that you lost the 10 points today doesn't mean that you can now earn an extra 10 rep beyond the rep cap today.