Is it safe to use Tretinoin 0.025% w/w Cream together with another product containing kojic acid, applying it twice a week?

Combining tretinoin with a kojic acid-based product isn't unusual, but both can be drying or irritating on their own, so layering them needs a bit of care - alternating nights rather than applying together is often gentler on the skin. Starting twice a week is a reasonable, cautious pace. It's still worth having your dermatologist confirm the exact routine so your skin barrier stays comfortable.