How are Puzzles grades on Lichess

Apart from the topic heading, how on earth are the puzzles graded some seem very easy and score 15+ points while others in my opinion are much harder but only receive 4 points!

your thoughts are welcome!!

I think it's part of the business. Rating system is quite funny as I've observe. But we should be grateful of it, bcoz we love playing chess, and chess puzzles are very helpful to improve our game.

It works as if the less people solves the puzzle, the more rating it has. And if your puzzle rating is lower than the puzzle's, it gives more point. Kinda like a chess match.

if you look at the analysis, you can see chess puzzles are taken from real games. So my guess is that it makes some kind of calculation based on player's rating. It's not really a great measurement, so I just use my puzzle score as a way to track progress

The puzzles have ratings, just like you do. When you play against a puzzle, you gain/lose rating just like when you win/lose a game of chess. The puzzle gains/loses rating as well.

In other words, puzzle training is rated just like games are. Individual puzzles have ratings just like humans do.