Is there sticky stuff all over the leaves? looks like an infestation.

Solids dissolved in water don't gas off like CO2 does, so as water evaporates, the level of dissolved solids increases, which is a backward step, even if small. Your pot has a drain hole - yes? Are you allowing your plant ti sit in the effluent that exits the drain hole? Your pot should be situated so it's always above the effluent that drains into the saucer - so there is no pathway by which the effluent can make its way back into the saucer. One way to set it up:

I'm not convinced you're not over-watering. The leaves that are malformed are likely the result of a culturally induced Ca deficiency. Too much water in the soil makes Ca uptake difficult. Even if the soil feels dry 2 knuckles deep, it can be wholly saturated at the pot bottom. Using a 'tell' is a very effective way to stay informed about what moisture levels are deep in the pot. The shedding of new leaves also goes hand-in-hand with over-watering.

Are you fertilizing regularly?

Examine the plant closely for scale and mites, either of which (as Dave notes) can cause the symptoms (other than the malformed leaves) shown. If no evidence of the bugly uggers, look to root health as the aspect most likely to need your proactivity.

Lots of tips/advice here.

Al

Hello guys,

I treated the plant against scale insects and there is progress already! Thank you!

https://ibb.co/FJy4pCw