Another interesting post by Martin about how Lineage and Samsung Android manage phone charging differently:
One odd thing I noticed is that LineageOS on the S9 behaves differently to Samsung’s stock android. While Lineage always stays in 9 V mode and increases the power draw, the Stock Android falls back to 5 V and reduces the power draw as soon as the screen is switched on. I tried with an S8 and saw the same behavior. I’m not sure why Samsung does this, perhaps to make sure the combined heat of charging, of running computing intensive tasks on the CPUs and the screen creating head doesn’t overheat the battery which would reduce its lifetime?