Why 23. c4?

Well, the knight looks good on d5 - but what does this piece really do? What does it attack what disturbs black that much? The bishop on the other hand is only on first look bad. It could come into play with the mentioned c4, on c5 it would become a real monster. It could go to g5 what happenend supporting the Rd2. It could go to h4.

Normally such a knight should not be exchanged with such a bishop, right. But if you look a little closer i would say exchange as much as you can as white due to your weak king.

Yeah, I dismissed c4 out of hand thinking it had no immediate value which was a mistake I see now @intro_bard_bot

Likewise, you are very tough! @vedanta_b_7

I figured the knights outpost is very strong and can't be challenged but I figured I could work around it seeing as it isn't directly attacking anything. @Ellen_Hall

I'll keep that in mind about your thoughts on exchanging pieces as white, I didn't really consider that it would be advantageous for white to do that. @royalblue04

Thanks again for the responses, it's helped me understand why I was wrong. I have a habit of discounting moves if I don't immediately see a value to it leading to worse positions as a result. Something I need to work on for sure.

@royalblue04 Right, and these are good points. The easy mistake though after recognizing the weaknesses in white's position is to immediately trade off the strong knight for the bishop though. White has a slight initiative and can use that to solidify his position (start defending f2 and d2 with Re2, at some point challenge the Rook on d4 and control the file, fix Black's pawns on dark squares). It's important to acknowledge that Black still needs to figure out a way to usefully activate the Bishop (and the queen is already putting pressure on d4, which is useful), and waiting on the exchange gives White time. Either Black decides to move his Bishop away which costs him a move, or White retains the tension. The balance hangs in Black's potential piece activity against White's weaker king vs White's potential positional advantage in an endgame.