This could simply be a problem with a period of no water.  House plants do frequently show different kinds of stress differently.  The Peace Lilly (Spathephylum)
will show first in the tips of the leaves and then the whole leaf will turn dry as is shown by your leaf.  Try cutting off he affected leaves at the base of the stem and water on a 7 to 10 day cycle to see if this situation turns around for you.

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