The reason that LA Knight was not involved on Smackdown last night was because he tested positive for COVID-19 and had to leave the building according to Sean Ross Sapp of Fightful.
It was bad timing for Knight as he was supposed to be involved in the main event closing angle, coming out to save John Cena from the attack of The Bloodline. Instead, creative changed and it was Cena who ended up being solo getting attacked by Sikoa and Uso.
Earlier in the broadcast, a tag match of Cena and AJ Styles vs Sikoa and Uso was teased but it was then said it will be for Fastlane and The Bloodline took out AJ Styles backstage, leaving Cena with no partner.
Cena still went out for the contract signing to end the show but Smackdown ended kinda flat as no one made the save for the 16-time world champion.