After examining the various nightlies, I have found the best possible version for curl and its library that works with LibreELEC 12.0.2 (stable). This applies to both the Generic(-legacy).x86_64 platform, as I have conducted extensive testing with it, and for RPi2/3, as these are my media players. The versions are curl and libcurl 8.5.0. curl&libcurl-8.5.0_Generic(-legacy).x86_64__&__RPi2~3.zip
This version also works well with higher LibreELEC versions. However, it does not work with lower ones!
Note: The file libcurl.so.4.8.0 consists of libcurl/8.5.0. One refers to a versioning for the Application Binary Interface (ABI), while the other pertains to the Application Programming Interface (API). I cannot provide an explanation of the differences, as I am not a coder.