I had no inacurracies, blunders or mistakes then also my centipawn loss was 48, or 50.
What is the problem here or I have misunderstood average centipawn loss.
You can have a look at that game at lichess. Link to the game: https://lichess.org/fhvYi9SS/black
Average centipawn loss is the difference of your move to the best computer move averaged over all moves.
Inaccuracies/Mistakes/blunders as defined per lichess are moves that are at least 0.5=50 centipawns / 1=100 centipawns / 3=300 centipawns worse than the suggested computer move.
This rule is not strictly enforced in situations where you have a clear winning position and a choice of several good moves.
So if you have a choice between a move that leads to +10 advantage (best computer move) and +9 advantage this will count to your centipawn loss, but will not show up as mistake.
Even without it, it is possible to collect centipawn losses < 50 that don't show up as inaccuracy.
I think the issue is that, when one side is winning by a large margin, the analysis will not always indicate an inaccuracy for a move which is not best but still clearly winning.
For example, after 20.Qg4, the analysis says that 20...dxe3 would have a score of -18.9, but your played move 20...d3 has a score of -10.9. That's an 800 centipawn difference. The analysis does not show an inaccuracy here, but that's a lot of centipawns.
I have thought (maybe too much, lol) a lot about this.
"Average centipawn loss (cpl) is the difference of your move to the best computer move averaged over all moves." Yes.
Like all averages this is pretty meaningless without some measure of variance. Very long games will tend to have a smaller cpl because of so many moves and there are not a lot of differences in the value of variations with only a few pieces left on the board. Simply put with lots of moves you are dividing by a larger number, there is little variance between move choices, and this yields a small cpl.
Also, there are games where the top 10 moves will vary in value very little e.g. closed positions like a stonewall. These games will show a low cpl.
I tend to play a very positional game where the positions end up with valuations that vary very little across any of the top 6-8 moves. These games show a low cpl. It does not mean I am playing well. It means the games are intrinsically calm, not sharp and tactical.
So if we had a measure of variance to go along with the cpl we would have a context to better understand what a cpl means. A 25 cpl with a high variance would mean you played rather well. A 25 cpl with a low variance would mean you played OK.
