This packaging bug is a big problem for Proton's Wine fork, which needs both /usr/lib/i386-linux-gnu/libgcrypt.so and /usr/lib/x86_64-linux-gnu/libgcrypt.so to be available at build time. Currently, Proton built for Debian can only support ECDH in 32-bit games or 64-bit games, but not both. See https://github.com/ValveSoftware/wine/commit/8ae2eb018d5b6ea97879f2acc4623afa4de6bc83
However, it won't do much good to fix libgcrypt20-dev without fixing its dependency libgpg-error-dev first. See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=933713
