The Football Association's updated requirements for transgender men to play in men's sports necessitate a declaration of being a "biological female" and acknowledging safety risks when competing against biological males.
"We are sorry to see Kay go but she leaves with our sincere thanks for her contribution to our winning England teams, particularly the development of the Lionesses pathway critical to the Euro success and the silver medal at the World Cup," FA chief executive Mark Bullingham said in a statement to BBC Sport.
Jackson was shown a red card by referee Lee Swabey for his protests after Newport were awarded a stoppage-time penalty for a foul by Huseyin Biler on Kyle Jameson. This incident underscored Jackson's passionate defense of his team's performance as they experienced a late turnaround in the match.
This is the moment for the Football Association to be proactive. John McDermott, the technical director, cannot stray into complacency and ignore the evidence from England's shambolic defeat by Greece.