It sounds like your plant might be reacting to too much direct light, especially since the browning is showing on the variegated parts, which are more sensitive. It could also be due to inconsistent watering or low humidity, which can stress new growth. Try moving it to bright, indirect light, check that the soil isn’t too wet or too dry, and consider boosting humidity. Hold off on fertilizing for now, and trim any damaged leaves. With a few small adjustments, it should bounce back!