Why was Williams goal disallowed for handball?

Nottingham Forest's Neco Williams had a headed goal ruled out during the goalless draw at Tottenham after VAR intervened for handball, though the exact contact isn't detailed beyond that. Referee Peter Bankes overturned the on-field decision, but Forest boss Oliver Glasner argued the call didn't meet the required clear-and-obvious threshold, accusing the official of "guessing" rather than having firm evidence [1, 2, 3].