As a native Russian speaker living in New York, I concur. I work in Ad Tech and deal with clients from Eastern Europe quite often. Russians' English is _always_ recognizable.
Nope, it's not. I always try to polish my English as much as I can, but after more than 8 years living in US, I still occasionally get messages from co-workers saying like, "hey dude, not to be pedantic, but ..."
If I were to write a long piece, you'd almost certainly notice that I'm not a native speaker. I'm subscribed to a few Telegram channels led by Russian speaking people and I always spot minor mistakes in their messages. Even when the text is grammatically correct, the way sentences are structured is what usually reveals them. I observe similar pattern with the partners I work with. Heck, even my English teacher's English (she is my friend on FB) is different from a typical writing style of a native speaker.
It obviously doesn't mean that Russians cannot learn a more "traditional" English, but when it comes to Russian hackers...meh, the chances are low, imho.
I think a native English speaker would have written either "I observe a similar pattern" or "I observe similar patterns". Your choice of words in that sentence feels russian to me (although I may be influenced knowing what you told earlier).
