Compatibility issues of slots when using the scratch swap method

[TwoBrushes]

Assuming that the primary slot has 64 sectors with a sector size of 1KB, the secondary slot has 32 sectors with a sector size of 2KB, and the scratch slot has 5 sectors with a sector size of 1KB (excluding the trailer size), the boot_slots_compatible(struct boot_loader_state *state) function should determine that the slots are compatible. Assuming the code is approximately 32KB, in the run_swap() function, sz = boot_copy_sz(state, last_sector_idx, &first_sector_idx), the return value of sz should be 5KB, since the sector indices in the input parameters are referenced to the primary slot. However, during the BOOT_STATUS_STATE_1 phase of the swap process, the secondary slot's sectors need to be erased. Since 5KB is not a boundary of the secondary slot, will erasing the secondary slot's sectors not erase the lower 1KB?