A bunch of divine moves! (review request)

[Lys]

Hi there!
I just played a game against doge_bot_3 and won. I’m very happy: it’s my first win against it.
I was white.

Training

Looking at katago analysis, there’s a move overlooked by both me and doggy.
It’s S15.
Katago wants it by both black and white since move 22.
Neither of us played it until move 142.

I don’t really get why it’s so important.

Black could gain few points and put some pressure on white’s group, in sente. Not bad. But quite small anyway.

For white, that settles the group in gote, when there’s still plenty of room to escape to the center.

So is it really that urgent or big?

Bonus feature: I played a move with a POSITIVE winrate! +4.6!!! And it wasn’t the biggest one! There was a +5 on the board!

Quite weird, isn’t it?

Any other advice is welcome, but my main question is about S15.

[Groin]

S15 is a urgent move. Urgent comes before big. When black takes it, white has only one eye. Besides it helps a bit to secure the corner.

After the exchange S15 R14 for example, a black move at N16 will cash big and same time threat to enclose white. And white with an eye only can’t plan any counter