SOLUTION:
I found another post on Reddit with the same problem - turns out the hard water is good for soft curly hair and adds grip! I checked the exact numbers and the water was significantly harder in Germany (28 °dH) than at home (8-18 °dH) which my soft curls needed! I added a tablespoon of kitchen salt (will buy some proper magnesium salt) to a bowl of water and rinced my hair in it, squeezed, applied mousse and gel like usual and diffused. The difference is HUGE (photo 3 in comments)!!!
I was on a trip in Germany where it was 80% humidity, raining and they have hard water. My curls have never been better!! Very fluffy, voluminous (photo 1). I washed it there twice, same great results. I come back home to Slovakia, wash my hair once and use the exact same products and my hair is completely different (photo 2)! They fall flat, dont curl as much, I have way less volume! How can I achieve the same results I had in Germany? I want that hair back!! 😅
Routine:
The products I used, in this order:
Loreal Metal Detox shampoo
Garnier Curl shampoo
Garnier Curl conditioner
Kerastase curl gellee
Umberto Gianni Curl mousse
Balea Locken Curls gel
Diffuzing on medium heat. Sleeping in a bonnet.