What is the reason for the yogurt-like texture that occurs when applying base makeup?

Lately, whenever I do my makeup, the base doesn't apply smoothly.
White, clumpy yogurt-like formations appear here and there.

Especially when applying foundation after sunscreen
The more I rubbed my face, the more it came off in small lumps.

I thought maybe it was because I applied too much base.
Even when I simply use toner and moisturizer, sometimes it pills just the same way.

Could this happen if the sunscreen and foundation aren't compatible?

How to apply base neatly without the yogurt-like texture, or
Is there a product combination that doesn't slide around easily?