Hi Aciel whilst the kernel for LE ARM8 CPU’s is aarch64 - thus the kernel is 64bit, the userland has been maintained as 32bit. There is a dependency on the vendor provided widevine library (one of the reasons why userland is maintained at 32bit)
The docker Addons is userland thus 32bit
https://wiki.libreelec.tv/development-1/build-commands/build-commands-le10
https://wiki.libreelec.tv/development-1/build-commands/build-addons
the =arm in the above build specifies that userland is compiled as 32bit. (Same for addons) whilst this can be changed for your use case, you would need to maintain the image and addons by self-compiling as the LE servers do not maintain a 64bit ARM8 addon repository.
Hope this helps