Recently I noticed some very suspicious patterns of downvoting. If you browse the rep pages of users on front weekly rep page you will see that almost all users received a pair of downvotes at the same time, yesterday. For example, in the 5 minutes 21:03 - 21:08 all of the following users received 1 or 2 downvotes (most got 2 downvotes at the same minute).
https://math.stackexchange.com/users/109865/igor-rivin?tab=reputation
https://math.stackexchange.com/users/83702/daniel-fischer?tab=reputation
https://math.stackexchange.com/users/63181/sami-ben-romdhane?tab=reputation
https://math.stackexchange.com/users/1650/martin-brandenburg?tab=reputation
https://math.stackexchange.com/users/53268/ron-gordon?tab=reputation
https://math.stackexchange.com/users/622/asaf-karagila?tab=reputation
https://math.stackexchange.com/users/59304/emanuele-paolini?tab=reputation
https://math.stackexchange.com/users/35667/eric-thoma?tab=reputation
https://math.stackexchange.com/users/6179/did?tab=reputation
https://math.stackexchange.com/users/79602/tim-ratigan?tab=reputation
https://math.stackexchange.com/users/115164/jeremy-daniel?tab=reputation
https://math.stackexchange.com/users/114173/alec?tab=reputation
https://math.stackexchange.com/users/31254/donantonio?tab=reputation
This pattern seems to continue for at least an hour (or at least it still occurs an hour later). Could the moderators or SE team please investigate. It seems very unlikely that these votes could have been made in good faith, so it is not fair that all of these valued contributors may waste time investigating possible problems with their answers (ditto for readers of these downvoted posts).