I'm using NCS 3.2.4. When USE_PARTITION_MANAGER is active, the ARM linker script defines ROM_SIZE as PM_SIZE (the full app partition) without subtracting CONFIG_ROM_END_OFFSET. This means the MCUboot swap trailer overhead computed by MCUboot's sysbuild module and propagated via CONFIG_ROM_END_OFFSET is not enforced by the linker.
As a result, an image can link successfully but be too large for MCUboot to swap at runtime, causing silent DFU failures where the device reports success but remains on the old firmware.
I have create a PR to fix the issue here: github.com/.../3876
