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8:46 AM
@GeraldEdgar I will just mention that another possible explanation of the decrease of reputation could be "user was removed" - as suggested by S. Carnahan. He also pointed out that the question I've mentioned in my previous comment was deleted in 2015 - so it cannot explain recent reputation decrease. (As I've mentioned, since I am below 10k, I wasn't able to check when the question was deleted.) — Martin Sleziak 23 secs ago
@S.Carnahan I have left there at least a comment briefly summarizing what you've told me.
I am unable to say much to that post. I still think that my answer is mostly right - negative number corresponds to reputation decrease. I was just incorrect about the reason.
Of course, if you want to add something more, feel free to comment there (or post your own answer if more details are needed).
In any case, thanks for looking into this.
 

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