Hi guys, what kind of deficiency is that? I think ...

Hard to tell in the coloured lighting, best to always take pics in white light or sunlight. Here is a link to a good leaf chart. Save this onto your desktop for reference read it over and it could help yea in the long run. https://420life.com/wp-content/uploads/2021/10/Marijuana-Leaf-Deficiency-Chart-scaled.jpg Just by the shading it could maybe be Potassium as it starts on the edges of the leaves but all the other pics in your diary looks normal and its not great to use colour light for diagnosis. Confirm your plant is receiving an adequate amount of NPK as well as CaSMg the secondary macros from your feeds labels. Most feeds are fine, but when groing in coir aka coco you need extra Ca and Mg as the medium intakes a lot of it for its own use on the cation exchange sites. also look like you took off some nodes on the plant, It might be a bit small for removing leaves. likely setting it back. Good Luck!