So, all payload who have NULL bytes inside works only in this versions, and of you try use curl extension in php you are limited to the same versions of the library that php should be compiled with. You can update README this it information. Curl developer no have plans to support NULL byte in gopher:// in future.
Curl gopher:// can send NULL byte only in 7.45.0 >= 7.71.0 versions Commit start support null byte Commit end support null byte
So, all payload who have NULL bytes inside works only in this versions, and of you try use curl extension in php you are limited to the same versions of the library that php should be compiled with. You can update README this it information. Curl developer no have plans to support NULL byte in gopher:// in future.