Watch this (top) one at 4.52. You can actually see Stephens' foot flex backwards when it meets his shin. Not his standing leg though, it was just off the ground.
https://www.ngolos.com/videos/2018-11-10-cardiff-brighton
For the first one, it was clearly flicked on from the head of an Albion player. For the second one, when their player headed it back towards the six yard box, Bamba was with Dunk - and it's difficult to see at the exact moment he headed it - but there were milliseconds between him being the...