So according to google, Paula's Choice and co.
"Probiotics boost the production of peptides, collagen and ceramides in your skin. This increases the elasticity of your skin, which in turn reduces the appearance of lines and wrinkles. Certain probiotics also reduce pores and have exfoliant properties that rejuvenate your skin."
"Benefits of prebiotics for skin
Keep the surface of skin—its first line of defense—balanced, younger-looking, and strong (3).
Offset factors that lead to redness, dryness, and a weakened surface (4).
Ward off signs of aging skin (4).
Restore a healthy microbiome balance (good bacteria) (2)."
And yes, I agree, my skin barrier is so nice when I use pre and probiotic skincare. My complexion is even and fresh, my skin is balanced, less oily etc.