In src/rp2_common/pico_crt0/embedded_start_block_inc.S the macro PICO_RP2040 is tested with #ifdef. Elsewhere in the SDK, PICO_RP2040 is expected to have a value of 0 for RP2350 and 1 for RP2040. #ifdef usage results in an incorrect ARM.attributes section generated when compiling crt0.S with PICO_RP2040=0 and PICO_RP2350=1 resulting in an un-bootable UF2.