Looking closer into this I noticed that this is an unsupported feature. If you want me to consider this change then I need you to do a pull request. There are development instructions in the readme ...

Hi! I've updated FastLED to new version and I'm getting this when trying to build project. c:\Users\niiik\Arduino\libraries\FastLED\src\platforms\esp\32\clockless_rmt_esp32.cpp: In member function ...