Using an example you posted: nostr:nevent1qqst7qducuu0mdx57e53f3cay84g6em47v8v0hpvvkjpsxthgrhk59gpz9mhxue69uhkummnw3ezuamfdejj7q3q7nd4yu9anyd3004pumgrtazaacujjxwzj36thtqsxskjy0r5urgqxpqqqqqqzanv8c9

What makes this painting so appealing?

I see there are only 3 striking colors, with variations where the paint mixes. He only uses big strokes and shapes. There is hardly any rendering. He uses dynamic directions that gives the painting movement so there is a lot of interesting stuff to look at.

What I would try replicating:
Use 3 colors
Use big shapes that lead the eye 
Use dark darks and light lights
Make sure the composition is interesting