Version `20.1.0` changes `armv8m.main_soft_nofp` to `armv8m.main_soft_nofp_unaligned`, thus: https://github.com/raspberrypi/pico-sdk/blob/ee68c78d0afae2b69c03ae1a72bf5cc267a2d94c/cmake/preload/toolchains/pico_arm_cortex_m33_clang.cmake#L4 need to reflect that change. There are `armv6m_soft_nofp` and `armv6m_soft_nofp_unaligned` as well, but `diff` says they're the same.