I found real life examples of Serverblight infestation on locally hoster publicly listed server.
I don't know why do bot hosters still host those.
I think it might be some item farming operation in disguise (because you don't have time to ban them and locally you cannot kick them)
Timestamps:
0:00 bot problem
3:05 asking questions
3:32 bonus footage No̱ 1
4:39 bonus footage No̱ 2
7:09 bonus footage No̱ 3
8:44 bonus footage No̱ 4
Edit:
Okay that's solved issue (edit: kinda, not really)
https://www.reddit.com/r/tf2/s/6nhDLMWRYu