
According to Grayscale, many investors are not aware of the bitcoin block reward halving.
As such, it still remains a key factor for the price and it is not completely priced in.
"We were surprised to learn that many of them were not even aware of this event." (Grayscale)
https://twitter.com/iamjosephyoung/status/1136949078879744000Very interesting news!

thank you
Edit: I found the original quote
Is the Halving Priced In?
The halving is close enough that its time to start talking about it more seriously, but far enough out in the future that its unclear whether its priced into the market efficiently. In fact, based on anecdotal conversations with market participants, we were surprised to learn that many of them were not even aware of this event. Moreover, according to Unchained Capital, less than 32% of the bitcoins in circulation have remained in the same wallet addresses since July 2016.3 This is consistent with our own determination that a large number of existing bitcoin holders are investors who have entered the market in the last three years. For many of them, this is uncharted territory and could very well be their first halving event.
While some investors in the digital asset ecosystem appear to have a short-term bias, strategies with a multi-year investment horizon and the discipline to hold strategic positions in Bitcoin through these events have historically generated outsized returns. For example, in the one-year periods following the first and second halvings, bitcoins price rose by roughly 81x and 3x, respectively.
https://grayscale.co/the-next-bitcoin-halving/Every time the halving comes near we get FUD with people saying its priced in.
So far post halving we have had a parabolic rise. I think we can safely say that no, the halving is never priced before it happens.
There are less coins being mined post halving therefore coins are more scarce. Its all about supply & demand, if you reduce the supply then demand increases which naturally makes the price go up.