Some of the leaves of my Spathiphyllum sprout with deformed edges. They don't turn yellow or brown at the tips over time - they start out like this. Oddly most leaves are perfectly normal and this only happens to about a third of the leaves.
I saw this a lot when I was doing interior plant maintenance. It is a burn due to high dissolved salts. It does not get better and often results in the plant being replaced due to the damage.
There are a few causes:
- if seen on new plants this indicates the grower did a last application of fertilizer that was too strong for the light levels at the home
- older plants can have this too and there are a few conditions that act together as triggers
- low light levels mean low growth rate
- peat based soil mix has a limited ability to buffer salts as it ages
- high ph alkaline water being used
For both causes I recommend
- moving to a higher light level
- doing a one time drench with distilled water. Pour enough through that water runs freely out of the bottom of the pot. The distilled water will lower the level of dissolved salts
- repotting with a mix of your choice. Tropical plant soil less potting mix is easy to find