Lapsus is from latin. And yes, it could mean blunder. But apart from being Latin the word is used in the English language as well. So why would it be "likely from Russian"?
I mean, doesn't prove anything. If they're smart they'd use the wrong language for their name. Or a double bluff...
"Oh, that 2021 date on yesterday's email? Sorry that was a lapsus" (but in Italian)