What's up with the anonymous downvoters?

Are these accounts bots? Or created by someone just to downvote posts? Most of them were created in November 2019 and February 2020 and have zero posts or comments. And judging by their names seems like they were created automatically. All they do is downvoting.

https://steemit.com/@postyj
https://steemit.com/@gresmol
https://steemit.com/@tijuanlin
https://steemit.com/@sheemgirl
https://steemit.com/@tsarnicolai
https://steemit.com/@joffri
https://steemit.com/@usako/
https://steemit.com/@nezbri
https://steemit.com/@islore
https://steemit.com/@friskot
https://steemit.com/@optiv
https://steemit.com/@bitarc
https://steemit.com/@trikosp
https://steemit.com/@drenus
https://steemit.com/@firgsia
https://steemit.com/@spojimceri
https://steemit.com/@seztik
https://steemit.com/@vramul
https://steemit.com/@netcrisk
https://steemit.com/@xujik
https://steemit.com/@jirtres