Carence qui arrive ?

Not a deficiency...........your plant is suffering with nitrogen toxicity from feeding too much or feeding too often .......... or both.

Well, the substrate looks really dry, so that is 'something'. This is usually climate-related or watering-related. I also sometimes see this on heavily shielded / congested areas occasionally. so, as far as irrigation.. 1) fully water entire volume. Never partially water. The entire thing should get saturated, this is normal and people that say otherwise is a red flag to stop listening to them. 2) Wait for appropriate dry-back (or loss of weight) and repeat. This can vary depending on the properties of your substrate - like water holding capacity. Somethign heavy, like a typical soil, you should wait until up to 1" deep dries on top. In something like coco coir that holds little water by comparison, you might re-irrigate the moment the top layer starts to change color from drying. weight is one of the best triggers. LEarn the weight of low-water vs fully irrigaetd and you just have to give the pot a little lift on the edge to determine watering need. If you follow these suggestions and get some wilting, that tells you to irrigate sooner with less dryback in future. Observe and adjust to reality - simple as that. Watering should be the easiest thing you do. It is mindless behaviour. As far as climate... make sure VPD is okay and this will ensure your temps and RH are in an appropriate range too. There's lots of reference tables for vpd that are color coded for seedling / vegetative / flower phase. You can google for that stuff. One other potential reason -- too much light. This is easy to rule out. If you took an indoor plant and put it outside, this is something you'd see as it tries to reduce surface area. This would quickly be followed by interveinal damage - sometimes in the course of a few hours. I had ad power outage 5-6 years ago, so i put my plant on the back deck and with 4-6 hours it was all droopy like that and top leaves already had interveinal light damage. That's a severe example, obviously. Life is a spectrum, not binary.

Its impossible to say with no info.How can anyone say you're underwatering when they have no idea how much you're watering.I'm giving some of mine 2ltrs a day.

100% you are under watering. When plants are in veg you need to let soil get dry between watering but durring the strech plants use a ton of water and you don’t need to let the soil get completely dry sometimes you have to water every other day durring the strech with a smaller pots. If you just water the plant every other day for a few days it should bounce back