Two main reasons sunscreen pills:
- not waiting long enough for previous products to be fully absorbed into the skin
- sunscreen and moisturizer not compatible with each other
Try waiting a few minutes for your moisturizer to completely absorb before applying sunscreen. If that doesn't work, try experimenting with other moisturizers that you may have. Not exfoliating enough can also contribute to pilling because of the accumulated dead skin.
I've tried the Skin1004 Hyalu-Cica sun serum and it never pilled on me, even with different moisturizers. It's the same for my sister too. I hope you find a solution for this. Something must have changed since it was working fine before