It was the same number of moves to mate regardless of whether the computer promoted the two extra queens, so I guess it didn't matter. Maybe the computer picked that line because it would have a higher material advantage with no extra moves required.
Savage Computer-Hard

If you look at the game, it is a little strange, it moves all its pawns to the 7th rank the shuffles the king around.

Computer played the finish like a douchebag human who thinks 'This guy should resign so I'll make 6 queens and move my king around to take the p**s'.

My only thought is that since it has to play so many games, maybe when the games are easily winning it gives less and less calculation power to that game.

Computer played the finish like a douchebag human who thinks 'This guy should resign so I'll make 6 queens and move my king around to take the p**s'.
When a human does it, you can challenge his motives.
But when an engine does it, maybe it's just the cold hard truth: people who don't resign are idiots.
https://www.chess.com/live/game/2041594280
This computer delayed the game for several moves just to get 3 queens. Why? What is this?