What actually triggers a 10% jump?

With the much needed and imo very welcome rally (short lived or not) it kinda got me wondering.

What exactly triggers a quick spike like this on such an enormous basis? I know market cap isn't necessarily the same as a similar cash amount of money flowing in, but how is it that seemingly "all of a sudden" people are willing to pay 10-20% more for BTC/selling it for 10-20% more?

Who are the buyers deciding to buy for higher prices now of all times?

I'm feeling pretty ignorant about this and I'm sure there is a logical explanation but other than "people are just paying more" I don't understand the dynamics of fast rallies like these, especially in the circumstances we are in right now.