Motorola's XML file does not seem to flash all partitions both in slot A and B. For safety purposes, in order to prevent hard bricks, it would be ideal that all partitions that have two slots, be flashed in both. LineageOS tries to solve this using a flashable .zip file that copies the current slot's partitions into the other slot, but
- I'm not sure if there's anything missing to be flashed
- Adding this as a step to the return to stock tutorial would feel weird, as it would involve downloading LineageOS' recovery or some other, then booting (not flashing, which could cause confusion) into it, and doing adb sideload on this file.
- Other people in XDA Forums seem to claim that these get flashed when the device is updated.
As long as one doesn't root, or mess with stock software more than they should, they should be fine. Also if someone's coming from CalyxOS which does flash both, they'll at least have something, though it might not exactly be signed by the correct keys so it might not work, can't check.