This is really unfortunate (and I don’t like her “policies” —like ANY FLOTUS should have “policies”) but I think this is the combination of using her “real” hair (w/a wiglet in the back?) being pulled back, the kitchen over head lighting (it’s a profession kitchen) and TV lighting. No doubt someone will not only be fired, but audited, deported or jailed.
I would guess (from hairline looking thinnish) that she has used weaves in the past (she can certainly afford top of the line) but that the “line” has ranged her real hair. I also believe she makes use of high end wigs.
ALL that said, somebody wasnt watching the monitors as this was being filmed, even an over head light correction would have made her visible.
Ranged = damaged