Stack Exchange network consists of 178 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
Q&A for work
Connect and share knowledge within a single location that is structured and easy to search.
Three hours ago someone downvoted without comment five of my recent contributions that have nothing in common but being five of my recent contributions. Should I be suspicious, and if so, is there something one should do?
There is nothing you should do, just wait for the serial voting reversal script to run. It runs once every 24 hours and reverses such abnormal voting patterns.