I was thinking "sunburn" or 'dry air", since you mentioned "near a window", but "fertilizer burn" seems more likely.
It looks dark green, so you could just withhold all fertilizer, especially high-nitrogen fertilizer, for a few weeks, to see if that helps.
It's always hard to tell from pictures of soil, but that soil looks dark and wet and maybe pretty fine. Is it well-enough aerated?
Does water come out freely the bottom when you water, or does the pot just absorb water like a camel going into the desert for a month?
If the soilless mix might be waterlogged, re-potting might be worth the effort. If the roots have not penetrated to the bottom of the pot, the mix may be too waterlogged for oxygen to reach the deeper parts of the pot. Sometimes "too much water" limits root growth so much that a little sun and dry draft can draw water out of the leaves faster than the few struggling roots can supply it. Hence wilting despite excess water.
If you don't want to re-pot, you can use a wicking mat to test whether the pot holds too much water.
Water it and wait until no more water comes out the bottom.
Heft it in your hands, or even weigh it, to see how much water it is holding.
Now set the pot down on top of a towel or any absorbent fabric that can touch the soil through the pot's holes. A towel can probably pull all the excess water out, but if you're using a Tee shirt, socks, or a cotton pillowcase, you ight have to dangle the end of the cloth off the edge of the table so excess water will drip down and out.
When water stops WICKING out of the pot, weigh it or heft it again to gauge how much water it was holding as "perched" water. Consider whether YOU would be very happy trying to breath THROUGH that deep a layer of water.
Plants in pots like good drainage.
(I kind of have a "drainage fetish", so listen carefully to Chelle and only try my games if you're interested or the soil DOES seems awfully damp.)