There are 4 plants there (it's hard to tell from the photo, sorry I didn't mentioned before). The one in the top left is the one having the problem, not sure if you are talking about the left at the bottom (I had some calcium deficiency a month ago due to low PH because the pen wasn't...
I just took a photo now, the photos I added 2 days ago where from the plant with the blue arrow, it's like 70% recovered. The other one it's pretty much the same, maybe a bit better
I can go up to 25°c, and I have a humidifier that works fine. I am lowering the temperature to see if they recover a bit, I can increase it later. Do you also think they are dehydrated due to the low humidity?
On top of the canopy I saw 24°c. I saw a small improvement in 1 of them, the other still the same. The leaves are dropped but also have the taco shape. Do you know how long does it take to recover?