I imagine this is in terms of PPP, and I don't see why Russia overtaking Germany, France, UK, or Brazil is in any way surprising. Pretty much, all the European countries are seeing their economies going into recession now, and it's not clear where Europe can get cheap energy at this point. The whole economic model Europe relied on is now invalidated. Meanwhile, Brazil has a large population, but Russia is still more industrialized as far as I know.

The reality is that the west intentionally undervalued Russian economy to paint Russia as being backwards. Russian rouble was one of the most undervalued currencies according to the big mac index https://www.economist.com/big-mac-index