Monstera Thai keeps browning

[raaain5outh]

Hello, my M.Thai leaf has kept browning on a leaf and is now half of what it use to be. I cut off the browning just leaving a little so it doesn't have a open wound for infection but she keeps browning. I haven't watered her since the last week of August since it's a lot colder now in Portland but she did get a full watering. Roots are healthy (filling the pot more since the last time I felt in there), she's also not soaked in water just moist, and has filtered light, humidifier is at 60-65% currently, hasn't been fertilized since I repotted her in April. She has had 4 leaves when I got her, 1 died, new leaf came up, back at 4 but slowly losing this one please help

 

[Kozu_yin]

It may be the sunlight, is she in an area of direct light?

 

[raaain5outh]

It may be the sunlight, is she in an area of direct light?

not at all. She currently has plant lights on her as it's more cloudy here now. Even then the lights are not as strong as what it used to get in the summer which it did well in.