The Newcastle winger scored the winner as his side beat the Gunners at St. James’ Park on November 4.
His strike was only awarded after a four-minute VAR check on three possible infringements.
Those included whether Willock had kept the ball in play before crossing it into the box.
Mikel Arteta slammed the match officials after the match, branding the decision to award the goal “a disgrace”.
He was subsequently charged by the FA for his comments, but has now escaped punishment after those charges were dropped.
An investigation into the incident has also revealed Willock told the Arsenal players the ball had gone out.
The Newcastle man had slid to keep it in play before his cross was knocked down by Joelinton for Gordon to score.
It is understood that the Arsenal players then told Arteta that Willock had admitted to failing to keep the ball in play.
This then increased what the Gunners boss described as his “sense of injustice and frustration”.
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Arteta had already been angered by the decision not to rule the goal out for offside or a foul by Joelinton after the lengthy VAR check.
Willock spent 17 years with Arsenal prior to his move to Newcastle in 2021.
After coming through the club’s academy, the midfielder scored 11 goals in 78 first-team appearances for the Gunners.