I once got banned for "vote brigading" on Reddit because I upvoted a crosspost that was deleted later, so this comes as no surprise. They have been monitoring upvotes and downvotes since forever.
When one community goes in mass to affect the votes in another.
E.g someone is doing a poll/vote, and you link that to somewhere else with the hope, or sometimes direct instructions to go vote on it in a certain way.
That's why reddit has cross-posts and the np (no participation, disables voting in the linked content) subdomain that try to keep the votes separated.
English is my third language, it's hard to remember which parts of it belong to a fourth one and shouldn't be translated (because "en masse" is literally French for "in mass")
If you cross-post, that sub gets it's own up/downvote count. You would have to open the link and go to the original post to see and affect them, so it already discourages brigading.
I got perma banned after i joined NAFO as a mod
2 bannes for petty reasons and then the third and final ban. Always waited for the other bans to time out