A pic pls. Socks may be right since these are not plants for direct sun at all. Semi-shade or bright, indirect light, but not direct sun.

It might be fungi

Karen - I tried to attach a photo earlier but I guess it didn’t work :/

It's Sunburn.

High light intensity levels can cause chlorophyll
molecules to rise to a more excited state than normal. If light
levels are high enough, the energy that is released as electrons in
molecules return to their normal energy state may be sufficient to
form oxygen radicals from O2. These are the same O2 negative radicals found
in H2O2 (hydrogen peroxide) and are extremely reactive particles that
readily destroy (oxidize/bleach) chlorophyll molecules. The entire process and technical term is photo oxidation, but we generally refer to it as sunburn.

Many confuse over-heating with photo-oxidation
(sunburn). They're different. I wouldn't put a plant in a direct sun
exposure and check daily for signs of burning. If your plant is
sunburned, a LOT of cells have been killed by the free oxygen
O-negative radical that's generated during photo over-exposure. IOW -
by the time there's a symptom, the damage has been done.

Overheating, OTOH, is caused by passive solar gain. Imagine how hot a dark
green car gets in intense direct sun when there is no breeze to get a
sense of what passive solar gain is - light energy being converted to
heat. Overheating commonly occurs indoors because of a layer of still
air (called the boundary layer) that surrounds the leaf serves to
insulate the leaf so heat is trapped in the leaf and not lost to
surrounding air. Most cases of overheating can be avoided by rigging
a fan on a timer so it disrupts the boundary layer during periods of
intense photo load.

Al

Just move it into the shade or inside so it doesn't get so much direct sun. It will recover. The pot has a hole in the bottom, right?

@socks the pot I have doesn’t have a hole so I put a bunch of rocks at the bottom before putting the plant in. I moved it to a shadier spot and it seems much happier. It has a lot of new baby leaves sprouting

Sorry, but pots must have a drainage hole. Sadly, the rocks in the bottom do little to help.

W/out a hole in the pot, it's usually just a question of time before the plant fails.

It doesn't have to have a drainage hole but it sure makes life easier if it did. Rocks in the bottom is a bad idea like Karen said.

Peace lilies are tough as nails - guess that is why it is so popular and sold a lot (for funerals since all 3 of mine have come from a funeral; grandmother in 85, brother in 97, and my dad in 2015).

I overwatered after not watering for weeks my first two and thought they were dead - tossed those on the compost heap where more compost and used potting soil went on top. The next spring I moved the pile to another location and found a green living plant miraculously alive and sprouting - it was one of the peace lilies. Digging a bit more I found the second one, sprouting new leaves too. I potted both up and still have them after a good ten years or so since that mishap. I add some potting soil every few years but rarely give them any special care or repot them. Tough. As. Nails. Just pinch off old leaves and new ones will soon come on.

Here is one of them this summer blooming away outdoors in some filtered sunlight.