Brazilian health authorities intervened on Sunday after accusing four Argentine Premier League players of violating the country's COVID-19 quarantine rules
Roberto Martinez's side are one of the clear favourites for Euro 2020 thanks to a host of star names who have propelled the Red Devils to the top of the FIFA rankings.
The two competitions are currently held every four years but the Saudi Arabian Football Federation (SAFF) put forward a proposal for a study of the impact of switching to every two years.
"We believe the future of football is at a critical juncture. The many issues that football has faced have now been further exacerbated by the ongoing pandemic," said SAFF president Yasser Al-Misehal.
UEFA said on Friday that the three clubs will face sanctions and European soccer's ruling body has started disciplinary proceedings against them.
The nine other clubs, including six English Premier League teams, backed out of the plan and have signed a "Club Commitment Declaration" including a series of reintegration steps.
"Whoever is considering joining a competition which is not authorized by UEFA, FIFA and FIGC will lose its membership", Gabriele Gravina was quoted as saying by Italian newsagency ANSA.
"We invite you to attend on an urgent basis discussion with us regarding the details of the competition and how it can best be accommodated within the football ecosystem," the letter concludes.
"We do not seek to replace the UEFA's Champions League or the Europa League but to compete with and exist alongside those tournaments," the letter read.
Right now there are programs under development to provide vaccination to all the attendees of the World Cup. We will be able, hopefully, to host a COVID-free event.
The president of global soccer body FIFA, Gianni Infantino, said in February that World Cup matches would play to full stadiums in Qatar next year.