Use this for delicate cakes. Angel food, sponge, chiffon, or a classic yellow cake. Anything that says “light as air.”
Do not use this for bread. Or pizza dough. Or cookies. They need that gluten muscle. Let them stay strong.
Also, avoid this swap if your recipe already calls for cake flour and only cake flour. Some recipes are divas. They will notice the substitution and get angry. But 90% of the time? You’re golden.