This is a known thing among chess players, and even low-skilled players do it to some extent. A newbie to chess can (and almost every teacher will say 'should') work their pattern recognition by just solving tactical chess puzzles and very quickly improve at spotting things like one or two move checkmate patterns or forks or pins or whatever.
It's more of a memory thing than subconscious calculation.
Sometimes it really looks like "calculations in the back of your head". Have you ever been struck with a 5 moves long tactics in positions you've never seen? Because I have.
There are hardly any other explanations than subconscious calculation.
Would you make the move based on vibes alone in a non-blitz game? The calculation is still required and it is faster for those already familiar.