Most of TeX Live is a redistribution of packages and programs from elsewhere, primarily CTAN. So, the target for bug reports varies according to the nature of the problem.
Highlights of changes in this release (details for pdfTeX, LuaTeX, XeTeX, MetaPost, dvips).
If you need to use alternate binaries, the custom binary support in the TL installer may be useful.
For x86_64-linux, we have built the subset of binaries which do not depend on icu and poppler on an older system (CentOS 6.10=glibc 2.12). They are available as a tarball (md5) and can be installed as custom binary set (q.v.).
Bug archives for the previous release and earlier years remain online.