Since 2022 there has been a huge effort to bootstrap GNU Guix in RISC-V machines. This effort required a full rewrite of the bootstrapping process of the distribution that is yet to be merged upstream, but it had other tangential outcomes.
During the process, some of the projects that are used during the bootstrapping had to be improved, most importantly GCC 4.6.4, a central piece of the bootstrapping chain, that had no RISC-V support (the RISC-V architecture was invented after GCC 4.6.4 was released).
GCC 4 is the latest GCC version that can be built with a C compiler (newer versions require C++) but can compile C++ code, which makes it a perfect bridge between simple C compilers and modern powerful compilers.
In the case of RISC-V, having a GCC 4.6.4 with RISC-V support makes possible to build it with a simple compiler like TinyCC and then use it to build GCC 7.5, the first GCC version with official RISC-V support, or higher.
This is why the mentioned bootstrapping effort forked GCC 4.6.4 and added RISC-V support to it, and now it's collectively maintained.